Organic light-emitting device

ABSTRACT

According to one or more embodiments, an organic light-emitting device includes: a first electrode; a second electrode; an emission layer between the first electrode and the second electrode; and a hole transport region between the first electrode and the emission layer. The hole transport region includes a first compound represented by Formula 1 and a second compound represented by Formula 2:

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to and the benefit of Korean Patent Application No. 10-2015-0060721, filed on Apr. 29, 2015, and Korean Patent Application No. 10-2016-0019167, filed on Feb. 18, 2016, in the Korean Intellectual Property Office, the entire contents of both are incorporated herein by reference.

BACKGROUND 1. Field

The following description relates to an organic light-emitting device.

2. Description of the Related Art

Organic light-emitting devices are self-emission devices that have wide viewing angles, high contrast ratios, short response times, and/or excellent brightness, driving voltage, and/or response speed characteristics, and may produce full-color images.

The organic light-emitting device may include a first electrode disposed on a substrate; and a hole transport region, an emission layer, an electron transport region, and a second electrode, which are sequentially disposed on the first electrode. Holes provided from the first electrode may move toward the emission layer through the hole transport region, and electrons provided from the second electrode may move toward the emission layer through the electron transport region. Carriers, such as holes and electrons, recombine in the emission layer to produce excitons. These excitons transition from an excited state to a ground state, thereby generating light.

SUMMARY

An aspect according to one or more embodiments of the present disclosure is directed toward an organic light-emitting device having low driving voltage, high efficiency, and/or long lifespan, and/or having improved low voltage efficiency.

Additional aspects will be set forth in part in the description which follows and, in part, will be apparent from the description, or may be learned by practice of the presented embodiments.

According to one or more embodiments, an organic light-emitting device includes:

-   -   a first electrode;     -   a second electrode;     -   an emission layer between the first electrode and the second         electrode; and     -   a hole transport region between the first electrode and the         emission layer,     -   wherein the hole transport region includes a first compound         represented by Formula 1 and a second compound represented by         Formula 2:

In Formulae 1 and 2 above,

-   -   X₁ and X₂ may each independently be selected from N, B, and P,     -   L₁ to L₆ may each independently be selected from a substituted         or unsubstituted C₃-C₁₀ cycloalkylene group, a substituted or         unsubstituted C₃-C₁₀ cycloalkenylene group, a substituted or         unsubstituted C₆-C₆₀ arylene group, and a substituted or         unsubstituted divalent non-aromatic condensed polycyclic group,     -   a1 to a6 may each independently be an integer selected from 0 to         3,     -   Ar₁ may be selected from a substituted or unsubstituted C₃-C₁₀         cycloalkyl group, a substituted or unsubstituted C₁-C₁₀         heterocycloalkyl group, a substituted or unsubstituted C₃-C₁₀         cycloalkenyl group, a substituted or unsubstituted C₁-C₁₀         heterocycloalkenyl group, a substituted or unsubstituted C₆-C₆₀         aryl group, a substituted or unsubstituted C₁-C₆₀ heteroaryl         group, a substituted or unsubstituted monovalent non-aromatic         condensed polycyclic group, and a substituted or unsubstituted         monovalent non-aromatic condensed heteropolycyclic group,     -   X₁₁ to X₁₃ may each independently be selected from groups         represented by Formulae 2A and 2B, and     -   c1 to c3 may each independently be an integer selected from 0 to         3, and a sum of c1, c2, and c3 may be one or more.     -   In Formulae 1, 2, 2A and 2B,     -   R₁ to R₁₁ may each independently be selected from hydrogen,         deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a         nitro group, an amino group, an amidino group, a hydrazine         group, a hydrazone group, a carboxylic acid group or a salt         thereof, a sulfonic acid group or a salt thereof, a phosphoric         acid group or a salt thereof, a substituted or unsubstituted         C₁-C₆₀ alkyl group, a substituted or unsubstituted C₂-C₆₀         alkenyl group, a substituted or unsubstituted C₂-C₆₀ alkynyl         group, a substituted or unsubstituted C₁-C₆₀ alkoxy group, a         substituted or unsubstituted C₃-C₁₀ cycloalkyl group, a         substituted or unsubstituted C₁-C₁₀ heterocycloalkyl group, a         substituted or unsubstituted C₃-C₁₀ cycloalkenyl group, a         substituted or unsubstituted C₁-C₁₀ heterocycloalkenyl group, a         substituted or unsubstituted C₆-C₆₀ aryl group, a substituted or         unsubstituted C₆-C₆₀ aryloxy group, a substituted or         unsubstituted C₆-C₆₀ arylthio group, a substituted or         unsubstituted C₁-C₆₀ heteroaryl group, a substituted or         unsubstituted monovalent non-aromatic condensed polycyclic         group, a substituted or unsubstituted monovalent non-aromatic         condensed heteropolycyclic group, and —Si(Q₁)(Q₂)(Q₃),     -   one selected from R₈(s) and one selected from R₉(s) in Formula         2A may be optionally connected to form a saturated or         unsaturated ring, and one selected from R₁₀(s) and one selected         from R₁₁(s) in Formula 2B may be optionally connected to form a         saturated or unsaturated ring,     -   b1 and b4 may each independently be an integer selected from 1         to 4,     -   b2, b3, and b9 to b11 may each independently be an integer         selected from 1 to 3,     -   b5 to b7 may each independently be an integer selected from 1 to         5,     -   b8 may be 1 or 2,     -   rings A₁ to A₄ may each independently be a benzene group or a         naphthalene group,     -   R₁₂ to R₁₅ may each independently be selected from a substituted         or unsubstituted C₁-C₆₀ alkyl group, a substituted or         unsubstituted C₃-C₁₀ cycloalkyl group, a substituted or         unsubstituted C₁-C₁₀ heterocycloalkyl group, a substituted or         unsubstituted C₃-C₁₀ cycloalkenyl group, a substituted or         unsubstituted C₁-C₁₀ heterocycloalkenyl group, a substituted or         unsubstituted C₆-C₆₀ aryl group, a substituted or unsubstituted         C₁-C₆₀ heteroaryl group, a substituted or unsubstituted         monovalent non-aromatic condensed polycyclic group, and a         substituted or unsubstituted monovalent non-aromatic condensed         heteropolycyclic group, and     -   at least one substituent of the substituted C₃-C₁₀ cycloalkylene         group, the substituted C₃-C₁₀ cycloalkenylene group, the         substituted C₆-C₆₀ arylene group, the substituted divalent         non-aromatic condensed polycyclic group, the substituted C₁-C₆₀         alkyl group, the substituted C₂-C₆₀ alkenyl group, the         substituted C₂-C₆₀ alkynyl group, the substituted C₁-C₆₀ alkoxy         group, the substituted C₃-C₁₀ cycloalkyl group, the substituted         C₁-C₁₀ heterocycloalkyl group, the substituted C₃-C₁₀         cycloalkenyl group, the substituted C₁-C₁₀ heterocycloalkenyl         group, the substituted C₆-C₆₀ aryl group, the substituted C₆-C₆₀         aryloxy group, the substituted C₆-C₆₀ arylthio group, the         substituted C₁-C₆₀ heteroaryl group, the substituted monovalent         non-aromatic condensed polycyclic group, and the substituted         monovalent non-aromatic condensed heteropolycyclic group may be         selected from the group consisting of:     -   deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a         nitro group, an amino group, an amidino group, a hydrazine         group, a hydrazone group, a carboxylic acid group or a salt         thereof, a sulfonic acid group or a salt thereof, a phosphoric         acid group or a salt thereof, a C₁-C₆₀ alkyl group, a C₂-C₆₀         alkenyl group, a C₂-C₆₀ alkynyl group, and a C₁-C₆₀ alkoxy         group;     -   a C₁-C₆₀ alkyl group, a C₂-C₆₀ alkenyl group, a C₂-C₆₀ alkynyl         group, and a C₁-C₆₀ alkoxy group, each substituted with at least         one selected from deuterium, —F, —Cl, —Br, —I, a hydroxyl group,         a cyano group, a nitro group, an amino group, an amidino group,         a hydrazine group, a hydrazone group, a carboxylic acid group or         a salt thereof, a sulfonic acid group or a salt thereof, a         phosphoric acid group or a salt thereof, a C₃-C₁₀ cycloalkyl         group, a C₁-C₁₀ heterocycloalkyl group, a C₃-C₁₀ cycloalkenyl         group, a C₁-C₁₀ heterocycloalkenyl group, a C₆-C₆₀ aryl group, a         C₆-C₆₀ aryloxy group, a C₆-C₆₀ arylthio group, a C₁-C₆₀         heteroaryl group, a monovalent non-aromatic condensed polycyclic         group, a monovalent non-aromatic condensed heteropolycyclic         group, a biphenyl group, a terphenyl group, and         —Si(Q₁₁)(Q₁₂)(Q₁₃);     -   a C₃-C₁₀ cycloalkyl group, a C₁-C₁₀ heterocycloalkyl group, a         C₃-C₁₀ cycloalkenyl group, a C₁-C₁₀ heterocycloalkenyl group, a         C₆-C₆₀ aryl group, a C₆-C₆₀ aryloxy group, a C₆-C₆₀ arylthio         group, a C₁-C₆₀ heteroaryl group, a monovalent non-aromatic         condensed polycyclic group, a monovalent non-aromatic condensed         heteropolycyclic group, a biphenyl group, and a terphenyl group;     -   a C₃-C₁₀ cycloalkyl group, a C₁-C₁₀ heterocycloalkyl group, a         C₃-C₁₀ cycloalkenyl group, a C₁-C₁₀ heterocycloalkenyl group, a         C₆-C₆₀ aryl group, a C₆-C₆₀ aryloxy group, a C₆-C₆₀ arylthio         group, a C₁-C₆₀ heteroaryl group, a monovalent non-aromatic         condensed polycyclic group, a monovalent non-aromatic condensed         heteropolycyclic group, a biphenyl group, and a terphenyl group,         each substituted with at least one selected from deuterium, —F,         —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an         amino group, an amidino group, a hydrazine group, a hydrazone         group, a carboxylic acid group or a salt thereof, a sulfonic         acid group or a salt thereof, a phosphoric acid group or a salt         thereof, a C₁-C₆₀ alkyl group, a C₂-C₆₀ alkenyl group, a C₂-C₆₀         alkynyl group, a C₁-C₆₀ alkoxy group, a C₃-C₁₀ cycloalkyl group,         a C₁-C₁₀ heterocycloalkyl group, a C₃-C₁₀ cycloalkenyl group, a         C₁-C₁₀ heterocycloalkenyl group, a C₆-C₆₀ aryl group, a C₆-C₆₀         aryloxy group, a C₆-C₆₀ arylthio group, a C₁-C₆₀ heteroaryl         group, a monovalent non-aromatic condensed polycyclic group, a         monovalent non-aromatic condensed heteropolycyclic group, a         biphenyl group, a terphenyl group, and —Si(Q₂₁)(Q₂₂)(Q₂₃); and     -   —Si(Q₃₁)(Q₃₂)(Q₃₃),     -   wherein Q₁ to Q₃, Q₁₁ to Q₁₃, Q₂₁ to Q₂₃, and Q₃₁ to Q₃₃ may         each independently be selected from hydrogen, deuterium, —F,         —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an         amino group, an amidino group, a hydrazine group, a hydrazone         group, a carboxylic acid group or a salt thereof, a sulfonic         acid group or a salt thereof, a phosphoric acid group or a salt         thereof, a C₁-C₆₀ alkyl group, a C₂-C₆₀ alkenyl group, a C₂-C₆₀         alkynyl group, a C₁-C₆₀ alkoxy group, a C₃-C₁₀ cycloalkyl group,         a C₁-C₁₀ heterocycloalkyl group, a C₃-C₁₀ cycloalkenyl group, a         C₁-C₁₀ heterocycloalkenyl group, a C₆-C₆₀ aryl group, a C₁-C₆₀         heteroaryl group, a monovalent non-aromatic condensed polycyclic         group, a monovalent non-aromatic condensed heteropolycyclic         group, a biphenyl group, and a terphenyl group; and     -   indicates a binding site to a neighboring atom.

BRIEF DESCRIPTION OF THE DRAWING

These and/or other aspects will become apparent and more readily appreciated from the following description of the embodiments, taken in conjunction with the drawing which is a schematic view of an organic light-emitting device according to an embodiment.

DETAILED DESCRIPTION

The drawing is a schematic view of an organic light-emitting device 10 according to an embodiment. The organic light-emitting device 10 may include a first electrode 110, a hole transport region 130, an emission layer 150, an electron transport region 170, and a second electrode 190. Herein, the first electrode 110 may be an anode, and the second electrode 190 may be a cathode.

Hereinafter, the structure of an organic light-emitting device according to an embodiment and a method of manufacturing an organic light-emitting device according to an embodiment will be described in connection with the drawing.

In the drawing, a substrate may be additionally disposed under the first electrode 110 or above the second electrode 190. The substrate may be a glass substrate or a transparent plastic substrate, each having excellent mechanical strength, thermal stability, transparency, surface smoothness, ease of handling, and/or water-resistance.

The first electrode 110 may be formed by depositing or sputtering a material for forming the first electrode 110 on the substrate. When the first electrode 110 is an anode, the material for forming the first electrode 110 may be selected from materials with a high work function to facilitate hole injection. The first electrode 110 may be a reflective electrode, a semi-transmissive electrode, or a transmissive electrode. The material for forming the first electrode 110 may be a transparent and highly conductive material, and examples of such a material are indium tin oxide (ITO), indium zinc oxide (IZO), tin oxide (SnO₂), and zinc oxide (ZnO). When the first electrode 110 is a semi-transmissive electrode or a reflective electrode, at least one selected from magnesium (Mg), aluminum (Al), aluminum-lithium (Al—Li), calcium (Ca), magnesium-indium (Mg—In), and magnesium-silver (Mg—Ag) may be utilized as a material for forming the first electrode 110.

The first electrode 110 may have a single-layered structure, or a multi-layered structure including two or more layers. For example, the first electrode 110 may have a three-layered structure of ITO/Ag/ITO, but the structure of the first electrode 110 is not limited thereto.

On the first electrode 110, the hole transport region 130, the emission layer 150, and the electron transport region 170 are sequentially stacked in this stated order.

The hole transport region 130 may include a first compound represented by Formula 1 and a second compound represented by Formula 2:

In Formulae 1 and 2,

-   -   X₁ and X₂ may each independently be selected from N, B, and P.

For example, X₁ and X₂ may be identical to or different from each other.

-   -   L₁ to L₆ in Formulae 1 and 2 may each independently be selected         from a substituted or unsubstituted C₃-C₁₀ cycloalkylene group,         a substituted or unsubstituted C₃-C₁₀ cycloalkenylene group, a         substituted or unsubstituted C₆-C₆₀ arylene group, and a         substituted or unsubstituted divalent non-aromatic condensed         polycyclic group.

For example, L₁ to L₆ in Formulae 1 and 2 may each independently be selected from the group consisting of:

-   -   a phenylene group, a pentalenylene group, an indenylene group, a         naphthylene group, an azulenylene group, a heptalenylene group,         an indacenylene group, an acenaphthylene group, a fluorenylene         group, a spiro-fluorenylene group, a benzofluorenylene group, a         dibenzofluorenylene group, a phenalenylene group, a         phenanthrenylene group, an anthracenylene group, a         fluoranthenylene group, a triphenylenylene group, a pyrenylene         group, a chrysenylene group, a naphthacenylene group, a         picenylene group, a perylenylene group, a pentaphenylene group,         a hexacenylene group, a pentacenylene group, a rubicenylene         group, a coronenylene group, and an ovalenylene group; and     -   a phenylene group, a pentalenylene group, an indenylene group, a         naphthylene group, an azulenylene group, a heptalenylene group,         an indacenylene group, an acenaphthylene group, a fluorenylene         group, a spiro-fluorenylene group, a benzofluorenylene group, a         dibenzofluorenylene group, a phenalenylene group, a         phenanthrenylene group, an anthracenylene group, a         fluoranthenylene group, a triphenylenylene group, a pyrenylene         group, a chrysenylene group, a naphthacenylene group, a         picenylene group, a perylenylene group, a pentaphenylene group,         a hexacenylene group, a pentacenylene group, a rubicenylene         group, a coronenylene group, and an ovalenylene group, each         substituted with at least one selected from deuterium, —F, —Cl,         —Br, —I, a hydroxyl group, a cyano group, a nitro group, an         amino group, an amidino group, a hydrazine group, a hydrazone         group, a carboxylic acid group or a salt thereof, a sulfonic         acid group or a salt thereof, a phosphoric acid group or a salt         thereof, a C₁-C₂₀ alkyl group, a C₁-C₂₀ alkoxy group, a         cyclopentyl group, a cyclohexyl group, a cycloheptyl group, a         cyclopentenyl group, a cyclohexenyl group, a phenyl group, a         biphenyl group, a terphenyl group, a pentalenyl group, an         indenyl group, a naphthyl group, an azulenyl group, a heptalenyl         group, an indacenyl group, an acenaphthyl group, a fluorenyl         group, a spiro-fluorenyl group, a benzofluorenyl group, a         dibenzofluorenyl group, a phenalenyl group, a phenanthrenyl         group, an anthracenyl group, a fluoranthenyl group, a         triphenylenyl group, a pyrenyl group, a chrysenyl group, a         naphthacenyl group, a picenyl group, a perylenyl group, a         pentaphenyl group, a hexacenyl group, a pentacenyl group, a         rubicenyl group, a coronenyl group, and an ovalenyl group.

In various embodiments, L₁ to L₆ in Formulae 1 and 2 may each independently be selected from the group consisting of:

-   -   a phenylene group, a naphthylene group, a fluorenylene group, a         spiro-fluorenylene group, a phenanthrenylene group, an         anthracenylene group, a fluoranthenylene group, a         triphenylenylene group, a pyrenylene group, and a chrysenylene         group; and     -   a phenylene group, a naphthylene group, a fluorenylene group, a         spiro-fluorenylene group, a phenanthrenylene group, an         anthracenylene group, a fluoranthenylene group, a         triphenylenylene group, a pyrenylene group, and a chrysenylene         group, each substituted with at least one selected from         deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a         nitro group, an amino group, an amidino group, a hydrazine         group, a hydrazone group, a carboxylic acid group or a salt         thereof, a sulfonic acid group or a salt thereof, a phosphoric         acid group or a salt thereof, a C₁-C₂₀ alkyl group, a C₁-C₂₀         alkoxy group, a phenyl group, a biphenyl group, a terphenyl         group, a naphthyl group, a fluorenyl group, a spiro-fluorenyl         group, a phenanthrenyl group, an anthracenyl group, a         fluoranthenyl group, a triphenylenyl group, a pyrenyl group, a         chrysenyl group, and —Si(Q₃₁)(Q₃₂)(Q₃₃),     -   wherein Q₃₁ to Q₃₃ may each independently be selected from a         C₁-C₂₀ alkyl group, a C₁-C₂₀ alkoxy group, a phenyl group, a         biphenyl group, a terphenyl group, and a naphthyl group.

In various embodiments, L₁ to L₆ in Formulae 1 and 2 may each independently be selected from groups represented by Formulae 3-1 to 3-11:

-   -   wherein, in Formulae 3-1 to 3-11,     -   Y₁ may be C(Z₃)(Z₄);     -   Z₁ to Z₄ may each independently be selected from hydrogen,         deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a         nitro group, an amino group, an amidino group, a hydrazine         group, a hydrazone group, a carboxylic acid group or a salt         thereof, a sulfonic acid group or a salt thereof, a phosphoric         acid group or a salt thereof, a C₁-C₂₀ alkyl group, a C₁-C₂₀         alkoxy group, a phenyl group, a biphenyl group, a terphenyl         group, a naphthyl group, a fluorenyl group, a spiro-fluorenyl         group, a benzofluorenyl group, a dibenzofluorenyl group, a         phenanthrenyl group, an anthracenyl group, a pyrenyl group, and         a chrysenyl group, and     -   d1 may be an integer selected from 1, 2, 3, and 4, d2 may be an         integer selected from 1, 2, and 3, d3 may be an integer selected         from 1, 2, 3, 4, 5, and 6, d4 may be an integer selected from 1,         2, 3, 4, 5, 6, 7, and 8, d5 may be an integer selected from 1,         2, 3, 4, and 5, and * and *′ indicate binding sites to a         neighboring atom.

In various embodiments, L₁ to L₆ may each independently be selected from groups represented by Formulae 4-1 to 4-13:

-   -   * and *′ in Formulae 4-1 to 4-13 indicate binding sites to a         neighboring atom.     -   a1 to a6 in Formulae 1 and 2 may each independently be an         integer selected from 0 to 3.     -   a1 indicates the number of L₁(s) and may be an integer selected         from 0 to 3. For example, when a1 in Formula 1 is zero,         *-(L₁)_(a1)-*′ may be a single bond; and when a1 is two or more,         two or more L₁(s) may be identical to or different from each         other.     -   a2 to a6 may each be the same as described herein in connection         with a1 and may be understood by referring to the structures of         Formulae 1 and 2.

For example, in Formula 1, a1 to a3 may be:

-   -   a1=1, a2=0, and a3=0;     -   a1=0, a2=1, and a3=0; or     -   a1=0, a2=0, and a3=1.

For example, in Formula 1, a1=0, a2=1, and a3=0.

In various embodiments, in Formula 2, a4 to a6 may be:

-   -   a4=a5=a6=1;     -   a4=1, a5=0, and a6=0;     -   a4=0, a5=1, and a6=0;     -   a4=0, a5=0, and a6=1;     -   a4=1, a5=1, and a6=0;     -   a4=0, a5=1, and a6=1; or     -   a4=1, a5=0, and a6=1.     -   Ar₁ in Formula 1 may be selected from a substituted or         unsubstituted C₃-C₁₀ cycloalkyl group, a substituted or         unsubstituted C₁-C₁₀ heterocycloalkyl group, a substituted or         unsubstituted C₃-C₁₀ cycloalkenyl group, a substituted or         unsubstituted C₁-C₁₀ heterocycloalkenyl group, a substituted or         unsubstituted C₆-C₆₀ aryl group, a substituted or unsubstituted         C₁-C₆₀ heteroaryl group, a substituted or unsubstituted         monovalent non-aromatic condensed polycyclic group, and a         substituted or unsubstituted monovalent non-aromatic condensed         heteropolycyclic group.

For example, Ar₁ in Formula 1 may be selected from the group consisting of:

-   -   a phenyl group, a biphenyl group, a terphenyl group, a naphthyl         group, a fluorenyl group, a spiro-fluorenyl group, a         benzofluorenyl group, a dibenzofluorenyl group, a phenanthrenyl         group, an anthracenyl group, a triphenylenyl group, a pyrenyl         group, a chrysenyl group, a pyrrolyl group, a thiophenyl group,         a furanyl group, an imidazolyl group, a pyrazolyl group, a         thiazolyl group, an isothiazolyl group, an oxazolyl group, an         isoxazolyl group, a pyridinyl group, a pyrazinyl group, a         pyrimidinyl group, a pyridazinyl group, a quinolinyl group, an         isoquinolinyl group, a benzoquinolinyl group, a quinoxalinyl         group, a quinazolinyl group, a carbazolyl group, a         benzimidazolyl group, a benzofuranyl group, a benzothiophenyl         group, an isobenzothiazolyl group, a benzoxazolyl group, an         isobenzoxazolyl group, an oxadiazolyl group, a triazinyl group,         a dibenzofuranyl group, a dibenzothiophenyl group, an         imidazopyridinyl group, and an imidazopyrimidinyl group; and     -   a phenyl group, a biphenyl group, a terphenyl group, a naphthyl         group, a fluorenyl group, a spiro-fluorenyl group, a         benzofluorenyl group, a dibenzofluorenyl group, a phenanthrenyl         group, an anthracenyl group, a triphenylenyl group, a pyrenyl         group, a chrysenyl group, a pyrrolyl group, a thiophenyl group,         a furanyl group, an imidazolyl group, a pyrazolyl group, a         thiazolyl group, an isothiazolyl group, an oxazolyl group, an         isoxazolyl group, a pyridinyl group, a pyrazinyl group, a         pyrimidinyl group, a pyridazinyl group, a quinolinyl group, an         isoquinolinyl group, a benzoquinolinyl group, a quinoxalinyl         group, a quinazolinyl group, a carbazolyl group, a         benzimidazolyl group, a benzofuranyl group, a benzothiophenyl         group, an isobenzothiazolyl group, a benzoxazolyl group, an         isobenzoxazolyl group, an oxadiazolyl group, a triazinyl group,         a dibenzofuranyl group, a dibenzothiophenyl group, an         imidazopyridinyl group, and an imidazopyrimidinyl group, each         substituted with at least one selected from deuterium, —F, —Cl,         —Br, —I, a hydroxyl group, a cyano group, a nitro group, an         amino group, an amidino group, a hydrazine group, a hydrazone         group, a carboxylic acid group or a salt thereof, a sulfonic         acid group or a salt thereof, a phosphoric acid group or a salt         thereof, a C₁-C₁₀ alkyl group, a C₁-C₁₀ alkoxy group, a phenyl         group, a biphenyl group, a terphenyl group, a naphthyl group, a         fluorenyl group, a spiro-fluorenyl group, a benzofluorenyl         group, a dibenzofluorenyl group, a phenanthrenyl group, an         anthracenyl group, a triphenylenyl group, a pyrenyl group, a         chrysenyl group, a pyrrolyl group, a thiophenyl group, a furanyl         group, an imidazolyl group, a pyrazolyl group, a thiazolyl         group, an isothiazolyl group, an oxazolyl group, an isoxazolyl         group, a pyridinyl group, a pyrazinyl group, a pyrimidinyl         group, a pyridazinyl group, a quinolinyl group, an isoquinolinyl         group, a benzoquinolinyl group, a quinoxalinyl group, a         quinazolinyl group, a carbazolyl group, a benzimidazolyl group,         a benzofuranyl group, a benzothiophenyl group, an         isobenzothiazolyl group, a benzoxazolyl group, an         isobenzoxazolyl group, an oxadiazolyl group, a triazinyl group,         a dibenzofuranyl group, a dibenzothiophenyl group, an         imidazopyridinyl group, an imidazopyrimidinyl group, and         —Si(Q₃₁)(Q₃₂)(Q₃₃),     -   wherein Q₃₁ to Q₃₃ may each independently be selected from a         C₁-C₁₀ alkyl group, a C₁-C₁₀ alkoxy group, a phenyl group, and a         naphthyl group.

In various embodiments, Ar₁ in Formula 1 may be selected from the group consisting of:

-   -   a phenyl group, a biphenyl group, a terphenyl group, a naphthyl         group, an anthracenyl group, a fluorenyl group, a phenanthrenyl         group, a pyridinyl group, a pyrimidinyl group, a triazinyl         group, a dibenzofuranyl group, and a dibenzothiophenyl group;         and     -   a phenyl group, a biphenyl group, a terphenyl group, a naphthyl         group, an anthracenyl group, a fluorenyl group, a phenanthrenyl         group, a pyridinyl group, a pyrimidinyl group, a triazinyl         group, a dibenzofuranyl group, and a dibenzothiophenyl group,         each substituted with at least one selected from deuterium, —F,         —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an         amino group, an amidino group, a hydrazine group, a hydrazone         group, a carboxylic acid group or a salt thereof, a sulfonic         acid group or a salt thereof, a phosphoric acid group or a salt         thereof, a C₁-C₁₀ alkyl group, a C₁-C₁₀ alkoxy group, a phenyl         group, a biphenyl group, a terphenyl group, a naphthyl group, an         anthracenyl group, a fluorenyl group, a phenanthrenyl group, a         pyridinyl group, a pyrimidinyl group, a triazinyl group, a         dibenzofuranyl group, a dibenzothiophenyl group, and         —Si(Q₃₁)(Q₃₂)(Q₃₃),     -   wherein Q₃₁ to Q₃₃ may each independently be selected from a         C₁-C₁₀ alkyl group, a C₁-C₁₀ alkoxy group, a phenyl group, and a         naphthyl group.     -   X₁₁ to X₁₃ in Formula 2 may each independently be selected from         groups represented by Formulae 2A and 2B:

Rings A₁ to A₄ in Formulae 2A and 2B may each independently be a benzene group or a naphthalene group.

For example, rings A₁ to A₄ in Formulae 2A and 2B may each independently be a benzene group.

One selected from R₈(s) and one selected from R₉(s) in Formula 2A may be optionally connected to form a saturated or unsaturated ring; and one selected from R₁₀(s) and one selected from R₁₁(s) in Formula 2B may be optionally connected to form a saturated or unsaturated ring.

In the Formulae above, R₁ to R₁₁ may each independently be selected from hydrogen, deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amino group, an amidino group, a hydrazine group, a hydrazone group, a carboxylic acid group or a salt thereof, a sulfonic acid group or a salt thereof, a phosphoric acid group or a salt thereof, a substituted or unsubstituted C₁-C₆₀ alkyl group, a substituted or unsubstituted C₂-C₆₀ alkenyl group, a substituted or unsubstituted C₂-C₆₀ alkynyl group, a substituted or unsubstituted C₁-C₆₀ alkoxy group, a substituted or unsubstituted C₃-C₁₀ cycloalkyl group, a substituted or unsubstituted C₁-C₁₀ heterocycloalkyl group, a substituted or unsubstituted C₃-C₁₀ cycloalkenyl group, a substituted or unsubstituted C₁-C₁₀ heterocycloalkenyl group, a substituted or unsubstituted C₆-C₆₀ aryl group, a substituted or unsubstituted C₆-C₆₀ aryloxy group, a substituted or unsubstituted C₆-C₆₀ arylthio group, a substituted or unsubstituted C₁-C₆₀ heteroaryl group, a substituted or unsubstituted monovalent non-aromatic condensed polycyclic group, a substituted or unsubstituted monovalent non-aromatic condensed heteropolycyclic group, and —Si(Q₁)(Q₂)(Q₃). Q₁ to Q₃ are the same as described herein.

For example, X₁₁ to X₁₃ in Formula 2 may each independently be selected from groups represented by Formulae 2A(1) to 2A(4) and 2B(1):

In Formulae 2A(1) to 2A(4) and 2B(1), R_(8a) is the same as described in connection with R₈, R_(9a) is the same as described in connection with R₉, R_(10a) is the same as described in connection with R₁₀, R_(11a) is the same as described in connection with R₁₁, b8a may be an integer selected from 1 to 3, and b9a to b11a may each independently be an integer selected from 1 to 4. One selected from R_(8a)(s) and one selected from R_(9a)(s) in Formulae 2A(1) to 2A(4) may be optionally connected to form a saturated or unsaturated ring, one selected from R_(10a)(s) and one selected from R_(11a)(s) in Formula 2B(1) may be optionally connected to form a saturated or unsaturated ring, and * indicates a binding site to a neighboring atom.

In various embodiments, X₁₁ to X₁₃ in Formula 2 may each independently be selected from groups represented by Formulae 2A(5) to 2A(7) and 2B(2):

In Formulae 2A(5) to 2A(7) and 2B(2), R_(8b) is the same as described in connection with R₈, R_(9b) is the same as described in connection with R₉, R_(10b) is the same as described in connection with R₁₀, R_(11b) is the same as described in connection with R₁₁, b8b may be 1 or 2, b9b to b11b may each independently be an integer selected from 1 to 3, and * indicates a binding site to a neighboring atom.

In various embodiments, Formula 2B may be selected from groups represented by Formulae 2B(1)1 to 2B(1)5:

In Formulae 2B(1)1 to 2B(1)5, R_(10a) is the same as described in connection with R₁₀, R_(11a) is the same as described in connection with R₁₁, and * indicates a binding site to a neighboring atom.

-   -   c1 to c3 in Formula 2 may each independently be an integer         selected from 0 to 3; and the sum of c1, c2, and c3 may be one         or more.     -   c1 in Formula 2 indicates the number of X₁₁(s), wherein when c1         is two or more, two or more X₁₁(s) may be identical to or         different from each other. c2 and c3 in Formula 2 may be the         same as described herein in connection with c1 and may be         understood by referring to the structure of Formula 2.

For example, the sum of c1, c2, and c3 in Formula 2 may be 1 or 2.

In the Formulae above,

-   -   b1 and b4 may each independently be an integer selected from 1         to 4;     -   b2, b3, and b9 to b11 may each independently be an integer         selected from 1 to 3;     -   b5 to b7 may each independently be an integer selected from 1 to         5; and     -   b8 may be 1 or 2.     -   b1 in the Formulae above indicates the number of R₁(s), wherein         when b1 is two or more, two or more R₁(s) may be identical to or         different from each other. b2 to b11 may be the same as         described herein in connection with b1 and may be understood by         referring to the structures of the Formulae above.     -   R₁₂ to R₁₅ in the Formulae above may each independently be         selected from a substituted or unsubstituted C₁-C₆₀ alkyl group,         a substituted or unsubstituted C₃-C₁₀ cycloalkyl group, a         substituted or unsubstituted C₁-C₁₀ heterocycloalkyl group, a         substituted or unsubstituted C₃-C₁₀ cycloalkenyl group, a         substituted or unsubstituted C₁-C₁₀ heterocycloalkenyl group, a         substituted or unsubstituted C₆-C₆₀ aryl group, a substituted or         unsubstituted C₁-C₆₀ heteroaryl group, a substituted or         unsubstituted monovalent non-aromatic condensed polycyclic         group, and a substituted or unsubstituted monovalent         non-aromatic condensed heteropolycyclic group.

For example, R₁ to R₁₁ in the Formulae above may each independently be selected from the group consisting of:

-   -   hydrogen, deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano         group, a nitro group, an amino group, an amidino group, a         hydrazine group, a hydrazone group, a carboxylic acid group or a         salt thereof, a sulfonic acid group or a salt thereof, a         phosphoric acid group or a salt thereof, a C₁-C₂₀ alkyl group,         and a C₁-C₂₀ alkoxy group;     -   a phenyl group, a biphenyl group, a terphenyl group, a naphthyl         group, a fluorenyl group, a spiro-fluorenyl group, a         benzofluorenyl group, a dibenzofluorenyl group, a phenanthrenyl         group, an anthracenyl group, a triphenylenyl group, a pyrenyl         group, a chrysenyl group, a pyrrolyl group, a thiophenyl group,         a furanyl group, an imidazolyl group, a pyrazolyl group, a         thiazolyl group, an isothiazolyl group, an oxazolyl group, an         isoxazolyl group, a pyridinyl group, a pyrazinyl group, a         pyrimidinyl group, a pyridazinyl group, a quinolinyl group, an         isoquinolinyl group, a benzoquinolinyl group, a quinoxalinyl         group, a quinazolinyl group, a carbazolyl group, a         benzimidazolyl group, a benzofuranyl group, a benzothiophenyl         group, an isobenzothiazolyl group, a benzoxazolyl group, an         isobenzoxazolyl group, an oxadiazolyl group, a triazinyl group,         a dibenzofuranyl group, a dibenzothiophenyl group, an         imidazopyridinyl group, and an imidazopyrimidinyl group;     -   a phenyl group, a biphenyl group, a terphenyl group, a naphthyl         group, a fluorenyl group, a spiro-fluorenyl group, a         benzofluorenyl group, a dibenzofluorenyl group, a phenanthrenyl         group, an anthracenyl group, a triphenylenyl group, a pyrenyl         group, a chrysenyl group, a pyrrolyl group, a thiophenyl group,         a furanyl group, an imidazolyl group, a pyrazolyl group, a         thiazolyl group, an isothiazolyl group, an oxazolyl group, an         isoxazolyl group, a pyridinyl group, a pyrazinyl group, a         pyrimidinyl group, a pyridazinyl group, a quinolinyl group, an         isoquinolinyl group, a benzoquinolinyl group, a quinoxalinyl         group, a quinazolinyl group, a carbazolyl group, a         benzimidazolyl group, a benzofuranyl group, a benzothiophenyl         group, an isobenzothiazolyl group, a benzoxazolyl group, an         isobenzoxazolyl group, an oxadiazolyl group, a triazinyl group,         a dibenzofuranyl group, a dibenzothiophenyl group, an         imidazopyridinyl group, and an imidazopyrimidinyl group, each         substituted with at least one selected from deuterium, —F, —Cl,         —Br, —I, a hydroxyl group, a cyano group, a nitro group, an         amino group, an amidino group, a hydrazine group, a hydrazone         group, a carboxylic acid group or a salt thereof, a sulfonic         acid group or a salt thereof, a phosphoric acid group or a salt         thereof, a C₁-C₁₀ alkyl group, a C₁-C₁₀ alkoxy group, a phenyl         group, a biphenyl group, a terphenyl group, a naphthyl group, a         fluorenyl group, a spiro-fluorenyl group, a benzofluorenyl         group, a dibenzofluorenyl group, a phenanthrenyl group, an         anthracenyl group, a triphenylenyl group, a pyrenyl group, a         chrysenyl group, a pyrrolyl group, a thiophenyl group, a furanyl         group, an imidazolyl group, a pyrazolyl group, a thiazolyl         group, an isothiazolyl group, an oxazolyl group, an isoxazolyl         group, a pyridinyl group, a pyrazinyl group, a pyrimidinyl         group, a pyridazinyl group, a quinolinyl group, an isoquinolinyl         group, a benzoquinolinyl group, a quinoxalinyl group, a         quinazolinyl group, a carbazolyl group, a benzimidazolyl group,         a benzofuranyl group, a benzothiophenyl group, an         isobenzothiazolyl group, a benzoxazolyl group, an         isobenzoxazolyl group, an oxadiazolyl group, a triazinyl group,         a dibenzofuranyl group, a dibenzothiophenyl group, an         imidazopyridinyl group, an imidazopyrimidinyl group, and         —Si(Q₃₁)(Q₃₂)(Q₃₃); and     -   —Si(Q₁)(Q₂)(Q₃).     -   R₁₂ to R₁₅ may each independently be selected from the group         consisting of:     -   a C₁-C₂₀ alkyl group and a C₁-C₂₀ alkoxy group;     -   a phenyl group, a biphenyl group, a terphenyl group, a naphthyl         group, a fluorenyl group, a spiro-fluorenyl group, a         benzofluorenyl group, a dibenzofluorenyl group, a phenanthrenyl         group, an anthracenyl group, a triphenylenyl group, a pyrenyl         group, a chrysenyl group, a pyrrolyl group, a thiophenyl group,         a furanyl group, an imidazolyl group, a pyrazolyl group, a         thiazolyl group, an isothiazolyl group, an oxazolyl group, an         isoxazolyl group, a pyridinyl group, a pyrazinyl group, a         pyrimidinyl group, a pyridazinyl group, a quinolinyl group, an         isoquinolinyl group, a benzoquinolinyl group, a quinoxalinyl         group, a quinazolinyl group, a carbazolyl group, a         benzimidazolyl group, a benzofuranyl group, a benzothiophenyl         group, an isobenzothiazolyl group, a benzoxazolyl group, an         isobenzoxazolyl group, an oxadiazolyl group, a triazinyl group,         a dibenzofuranyl group, a dibenzothiophenyl group, an         imidazopyridinyl group, and an imidazopyrimidinyl group;     -   a phenyl group, a biphenyl group, a terphenyl group, a naphthyl         group, a fluorenyl group, a spiro-fluorenyl group, a         benzofluorenyl group, a dibenzofluorenyl group, a phenanthrenyl         group, an anthracenyl group, a triphenylenyl group, a pyrenyl         group, a chrysenyl group, a pyrrolyl group, a thiophenyl group,         a furanyl group, an imidazolyl group, a pyrazolyl group, a         thiazolyl group, an isothiazolyl group, an oxazolyl group, an         isoxazolyl group, a pyridinyl group, a pyrazinyl group, a         pyrimidinyl group, a pyridazinyl group, a quinolinyl group, an         isoquinolinyl group, a benzoquinolinyl group, a quinoxalinyl         group, a quinazolinyl group, a carbazolyl group, a         benzimidazolyl group, a benzofuranyl group, a benzothiophenyl         group, an isobenzothiazolyl group, a benzoxazolyl group, an         isobenzoxazolyl group, an oxadiazolyl group, a triazinyl group,         a dibenzofuranyl group, a dibenzothiophenyl group, an         imidazopyridinyl group, and an imidazopyrimidinyl group, each         substituted with at least one selected from deuterium, —F, —Cl,         —Br, —I, a hydroxyl group, a cyano group, a nitro group, an         amino group, an amidino group, a hydrazine group, a hydrazone         group, a carboxylic acid group or a salt thereof, a sulfonic         acid group or a salt thereof, a phosphoric acid group or a salt         thereof, a C₁-C₁₀ alkyl group, a C₁-C₁₀ alkoxy group, a phenyl         group, a biphenyl group, a terphenyl group, a naphthyl group, a         fluorenyl group, a spiro-fluorenyl group, a benzofluorenyl         group, a dibenzofluorenyl group, a phenanthrenyl group, an         anthracenyl group, a triphenylenyl group, a pyrenyl group, a         chrysenyl group, a pyrrolyl group, a thiophenyl group, a furanyl         group, an imidazolyl group, a pyrazolyl group, a thiazolyl         group, an isothiazolyl group, an oxazolyl group, an isoxazolyl         group, a pyridinyl group, a pyrazinyl group, a pyrimidinyl         group, a pyridazinyl group, a quinolinyl group, an isoquinolinyl         group, a benzoquinolinyl group, a quinoxalinyl group, a         quinazolinyl group, a carbazolyl group, a benzimidazolyl group,         a benzofuranyl group, a benzothiophenyl group, an         isobenzothiazolyl group, a benzoxazolyl group, an         isobenzoxazolyl group, an oxadiazolyl group, a triazinyl group,         a dibenzofuranyl group, a dibenzothiophenyl group, an         imidazopyridinyl group, an imidazopyrimidinyl group, and         —Si(Q₃₁)(Q₃₂)(Q₃₃); and     -   —Si(Q₁)(Q₂)(Q₃),     -   wherein Q₁ to Q₃ and Q₃₁ to Q₃₃ may each independently be         selected from a C₁-C₁₀ alkyl group, a C₁-C₁₀ alkoxy group, a         phenyl group, and a naphthyl group.

In various embodiments, R₁ to R₁₁ in Formulae above may each independently be selected from the group consisting of:

-   -   hydrogen, deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano         group, a nitro group, an amino group, an amidino group, a         hydrazine group, a hydrazone group, a carboxylic acid group or a         salt thereof, a sulfonic acid group or a salt thereof, a         phosphoric acid group or a salt thereof, a C₁-C₁₀ alkyl group,         and a C₁-C₁₀ alkoxy group;     -   a phenyl group, a biphenyl group, a terphenyl group, a naphthyl         group, a fluorenyl group, a spiro-fluorenyl group, a         benzofluorenyl group, a dibenzofluorenyl group, a phenanthrenyl         group, an anthracenyl group, a triphenylenyl group, a pyrenyl         group, a chrysenyl group, a carbazolyl group, a dibenzofuranyl         group, and a dibenzothiophenyl group;     -   a phenyl group, a biphenyl group, a terphenyl group, a naphthyl         group, a fluorenyl group, a spiro-fluorenyl group, a         benzofluorenyl group, a dibenzofluorenyl group, a phenanthrenyl         group, an anthracenyl group, a triphenylenyl group, a pyrenyl         group, a chrysenyl group, a carbazolyl group, a dibenzofuranyl         group, and a dibenzothiophenyl group, each substituted with at         least one selected from deuterium, —F, —Cl, —Br, —I, a hydroxyl         group, a cyano group, a nitro group, an amino group, an amidino         group, a hydrazine group, a hydrazone group, a carboxylic acid         group or a salt thereof, a sulfonic acid group or a salt         thereof, a phosphoric acid group or a salt thereof, a C₁-C₁₀         alkyl group, a C₁-C₁₀ alkoxy group, a phenyl group, a biphenyl         group, a terphenyl group, a naphthyl group, and         —Si(Q₃₁)(Q₃₂)(Q₃₃); and     -   —Si(Q₁)(Q₂)(Q₃).     -   R₁₂ to R₁₅ may each independently be selected from the group         consisting of:     -   a C₁-C₁₀ alkyl group and a C₁-C₁₀ alkoxy group;     -   a phenyl group, a biphenyl group, a terphenyl group, a naphthyl         group, a fluorenyl group, a spiro-fluorenyl group, a         benzofluorenyl group, a dibenzofluorenyl group, a phenanthrenyl         group, an anthracenyl group, a triphenylenyl group, a pyrenyl         group, a chrysenyl group, a carbazolyl group, a dibenzofuranyl         group, and a dibenzothiophenyl group;     -   a phenyl group, a biphenyl group, a terphenyl group, a naphthyl         group, a fluorenyl group, a spiro-fluorenyl group, a         benzofluorenyl group, a dibenzofluorenyl group, a phenanthrenyl         group, an anthracenyl group, a triphenylenyl group, a pyrenyl         group, a chrysenyl group, a carbazolyl group, a dibenzofuranyl         group, and a dibenzothiophenyl group, each substituted with at         least one selected from deuterium, —F, —Cl, —Br, —I, a hydroxyl         group, a cyano group, a nitro group, an amino group, an amidino         group, a hydrazine group, a hydrazone group, a carboxylic acid         group or a salt thereof, a sulfonic acid group or a salt         thereof, a phosphoric acid group or a salt thereof, a C₁-C₁₀         alkyl group, a C₁-C₁₀ alkoxy group, a phenyl group, a biphenyl         group, a terphenyl group, a naphthyl group, and         —Si(Q₃₁)(Q₃₂)(Q₃₃); and     -   —Si(Q₁)(Q₂)(Q₃),     -   wherein Q₁ to Q₃ and Q₃₁ to Q₃₃ may each independently be         selected from a C₁-C₁₀ alkyl group, a C₁-C₁₀ alkoxy group, a         phenyl group, a biphenyl group, a terphenyl group, and a         naphthyl group.

In various embodiments, Ar₁ in Formula 1 may be selected from groups represented by Formulae 5-1 to 5-19,

-   -   R₁ to R₁₁ may each independently be selected from hydrogen,         deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a         nitro group, an amino group, an amidino group, a hydrazine         group, a hydrazone group, a carboxylic acid group or a salt         thereof, a sulfonic acid group or a salt thereof, a phosphoric         acid group or a salt thereof, a C₁-C₁₀ alkyl group, a C₁-C₁₀         alkoxy group, and a group represented by any of Formulae 5-1 to         5-11, and     -   R₁₂ to R₁₅ may each independently be selected from a C₁-C₁₀         alkyl group, a C₁-C₁₀ alkoxy group, and a group represented by         any of Formulae 5-1 to 5-11:

-   -   wherein, in Formulae 5-1 to 5-19,     -   Y₃₁ may be selected from O, S, C(Z₃₃)(Z₃₄), N(Z₃₅), and         Si(Z₃₆)(Z₃₇),     -   Z₃₁ to Z₃₇ may each independently be selected from hydrogen,         deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a         nitro group, an amino group, an amidino group, a hydrazine         group, a hydrazone group, a carboxylic acid group or a salt         thereof, a sulfonic acid group or a salt thereof, a phosphoric         acid group or a salt thereof, a C₁-C₂₀ alkyl group, a C₁-C₂₀         alkoxy group, a phenyl group, a biphenyl group, a terphenyl         group, a naphthyl group, a fluorenyl group, a spiro-fluorenyl         group, a benzofluorenyl group, a dibenzofluorenyl group, a         phenanthrenyl group, an anthracenyl group, a pyrenyl group, a         chrysenyl group, a pyridinyl group, a pyrazinyl group, a         pyrimidinyl group, a pyridazinyl group, a quinolinyl group, an         isoquinolinyl group, a quinoxalinyl group, a quinazolinyl group,         a carbazolyl group, and a triazinyl group,     -   e1 may be an integer selected from 1 to 5, e2 may be an integer         selected from 1 to 7, e3 may be an integer selected from 1 to 3,         e4 may be an integer selected from 1 to 4, e5 may be an integer         selected from 1 and 2, e6 may be an integer selected from 1 to         6, and e7 may be an integer selected from 1 to 9, and     -   * indicates a binding site to a neighboring atom.

In various embodiments, Ar₁ in Formula 1 may be selected from groups represented by Formulae 6-1 to 6-26,

-   -   R₁ to R₁₁ may each independently be selected from hydrogen,         deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a         nitro group, an amino group, an amidino group, a hydrazine         group, a hydrazone group, a carboxylic acid group or a salt         thereof, a sulfonic acid group or a salt thereof, a phosphoric         acid group or a salt thereof, a C₁-C₁₀ alkyl group, a C₁-C₁₀         alkoxy group, and a group represented by any of Formulae 6-1 to         6-23, and     -   R₁₂ to R₁₅ may each independently be selected from a C₁-C₁₀         alkyl group, a C₁-C₁₀ alkoxy group, and a group represented by         any of Formulae 6-1 to 6-23:

-   -   * in Formulae 6-1 to 6-26 indicates a binding site to a         neighboring atom.

In various embodiments, the first compound may be represented by one selected from Formulae 1-1 to 1-4:

-   -   X₁, L₁ to L₃, a1 to a3, Ar₁, R₁₂ to R₁₄, R₁ to R₄, and b1 to b4         in Formulae 1-1 to 1-4 are the same as described above.

For example, a1 to a3 in Formulae 1-1 to 1-4 may each independently be 0 or 1.

In various embodiments, in Formulae 1-1 to 1-4, a1 and a3 may be 0, and a2 may be 1.

In various embodiments, the first compound may be represented by one selected from Formulae 1-1(1) and 1-1(2):

In Formulae 1-1(1) and 1-1(2), X₁, L₁, L₃, a1, a3, Ar₁, R₁ to R₄, b1 to b4, and R₁₄ are the same as described above, R₃₁ to R₃₃ are the same as described in connection with R₁, b31 may be an integer selected from 1 to 4, and b32 and b33 may each independently be an integer selected from 1 to 5.

In various embodiments, the second compound may be represented by one selected from Formulae 2-1 and 2-2:

In Formulae 2-1 and 2-2, X₂, X₁₁ to X₁₃, c1 to c3, R₅ to R₇, and b5 to b7 are the same as described above,

-   -   R₁₆ to R₁₈ are the same as described in connection with R₁, and         b16 to b18 may each independently be an integer selected from 1         to 4.

For example, R₁₆ to R₁₈ in Formulae 2-1 and 2-2 may each independently be selected from hydrogen, deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amino group, an amidino group, a hydrazine group, a hydrazone group, a carboxylic acid group or a salt thereof, a sulfonic acid group or a salt thereof, a phosphoric acid group or a salt thereof, a C₁-C₂₀ alkyl group, a C₁-C₂₀ alkoxy group, a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, a cyclopentenyl group, a cyclohexenyl group, a phenyl group, a biphenyl group, a terphenyl group, a pentalenyl group, an indenyl group, a naphthyl group, an azulenyl group, a heptalenyl group, an indacenyl group, an acenaphthyl group, a fluorenyl group, a spiro-fluorenyl group, a benzofluorenyl group, a dibenzofluorenyl group, a phenalenyl group, a phenanthrenyl group, an anthracenyl group, a fluoranthenyl group, a triphenylenyl group, a pyrenyl group, a chrysenyl group, a naphthacenyl group, a picenyl group, a perylenyl group, a pentaphenyl group, a hexacenyl group, a pentacenyl group, a rubicenyl group, a coronenyl group, and an ovalenyl group.

The first compound represented by Formula 1 may be one selected from Compounds 101 to 109; and the second compound represented by Formula 2 may be one selected from Compounds 1 to 22, but embodiments of the present disclosure are not limited thereto:

When the hole transport region 130 includes the first compound represented by Formula 1 and the second compound represented by Formula 2, a recombination balance (e.g., an optimal recombination balance) between holes and electrons may be achieved, thereby improving the efficiency and extending the lifespan of an organic light-emitting device.

The hole transport region may include at least one selected from a hole injection layer, a hole transport layer, a hole auxiliary layer, a buffer layer, and an electron blocking layer.

In various embodiments, the hole transport region 130 may include a hole transport layer and a hole auxiliary layer. The hole transport layer may include the first compound represented by Formula 1, and the hole auxiliary layer may include the second compound represented by Formula 2.

In various embodiments, the hole transport layer may include the first compound represented by one selected from Formulae 1-1 to 1-4 (e.g., one selected from Formulae 1-1 and 1-4), and the hole auxiliary layer may include the second compound represented by one selected from Formulae 2-1 and 2-2.

In various embodiments, the hole transport layer may include the first compound represented by one selected from Formulae 1-1(1) and 1-1(2), and the hole auxiliary layer may include the second compound represented by one selected from Formulae 2-1 and 2-2.

In various embodiments, the hole transport layer may include one selected from Compounds 101 to 109, and the hole auxiliary layer may include one selected from Compounds 1 to 22.

In various embodiments, the hole auxiliary layer may be disposed between the emission layer 150 and the first electrode 110; the hole transport layer may be disposed between the hole auxiliary layer and the first electrode 110; the hole transport layer may include the first compound represented by Formula 1; and the hole auxiliary layer may include the second compound represented by Formula 2.

The hole auxiliary layer may directly contact the emission layer.

For example, the hole transport region 130 may have a structure of hole injection layer/hole transport layer/hole auxiliary layer, a structure of hole injection layer/hole transport layer/buffer layer/hole auxiliary layer, a structure of hole transport layer/hole auxiliary layer, or a structure of hole transport layer/buffer layer/hole auxiliary layer, wherein, in each of these structures, constituting layers are sequentially stacked in this stated order from the first electrode 110, but the structure of the hole transport region 130 is not limited thereto.

When the hole transport region includes a hole injection layer, the hole injection layer may be formed on the first electrode 110 utilizing one or more suitable methods selected from vacuum deposition, spin coating, casting, langmuir-blodgett (LB) deposition, ink-jet printing, laser-printing, and laser-induced thermal imaging.

When a hole injection layer is formed by vacuum deposition, for example, the vacuum deposition may be performed at a deposition temperature of about 100° C. to about 500° C., at a vacuum degree of about 10⁻⁸ to about 10⁻³ torr, and at a deposition rate of about 0.01 to about 100 Å/sec by taking into account the material for the hole injection layer to be deposited, and the structure of the hole injection layer to be formed.

When a hole injection layer is formed by spin coating, the spin coating may be performed at a coating rate of about 2,000 rpm to about 5,000 rpm, and at a temperature of about 80° C. to 200° C. by taking into account the material for the hole injection layer to be deposited, and the structure of the hole injection layer to be formed.

Methods of forming the hole transport layer, the hole auxiliary layer, the buffer layer, and/or the electron blocking layer may be the same as described herein in connection with the method utilized to form the hole injection layer.

A thickness of the hole transport region 130 may be in a range of about 100 Å to about 10,000 Å, for example, about 100 Å to about 1,000 Å. When the hole transport region 130 includes the hole transport layer and the hole auxiliary layer, a thickness of the hole transport layer may be in a range of about 50 Å to about 2,000 Å, for example, about 100 Å to about 1,500 Å; and a thickness of the hole auxiliary layer may be in a range of about 20 Å to about 2,000 Å. When the hole transport region 130, the hole transport layer, and the hole auxiliary layer have these thickness ranges, satisfactory hole transport characteristics may be obtained without a substantial increase in the driving voltage.

The hole transport region may further include, in addition to the first compound and the second compound, at least one selected from m-MTDATA, TDATA, 2-TNATA, NPB, β-NPB, TPD, Spiro-TPD, Spiro-NPB, methylated-NPB, TAPC, HMTPD, 4,4′,4″-tris(N-carbazolyl)triphenylamine (TCTA), polyaniline/dodecylbenzenesulfonic acid (Pani/DBSA), poly(3,4-ethylenedioxythiophene)/poly(4-styrenesulfonate) (PEDOT/PSS), polyaniline/camphor sulfonic acid (Pani/CSA), and polyaniline/poly(4-styrenesulfonate) (PANI/PSS):

The hole transport region 130 may further include, in addition to these materials, a charge-generation material for the improvement of conductive properties. The charge-generation material may be homogeneously or non-homogeneously dispersed in the hole transport region.

The charge-generation material may be, for example, a p-dopant. The p-dopant may be one selected from a quinone derivative, a metal oxide, and a cyano group-containing compound, but embodiments of the present disclosure are not limited thereto. For example, non-limiting examples of the p-dopant are a quinone derivative (such as tetracyanoquinonedimethane (TCNQ) and/or 2,3,5,6-tetrafluoro-tetracyano-1,4-benzoquinonedimethane (F4-TCNQ)); a metal oxide (such as a tungsten oxide and/or a molybdenum oxide), and Compound HT-D1 illustrated below, but embodiments of the present disclosure are not limited thereto:

The hole transport region may further include, in addition to the hole transport layer and the hole auxiliary layer, at least one layer of a buffer layer and an electron blocking layer. Since the buffer layer may compensate for an optical resonance distance according to a wavelength of light emitted from the emission layer, light-emission efficiency of a formed organic light-emitting device may be improved. For usage as a material included in the buffer layer, materials that are suitable for the hole transport region may be utilized. The electron blocking layer may reduce or prevent injection of electrons from the electron transport region.

The emission layer 150 may be formed on the hole transport region 130 by one or more suitable methods selected from vacuum deposition, spin-coating, casting, LB deposition, inkjet printing, laser printing, and laser induced thermal imaging (LITI).

When the emission layer 150 is formed by vacuum deposition or spin-coating, deposition conditions and coating conditions for the forming of the emission layer 150 may be substantially the same as those utilized to form the hole injection layer.

The emission layer 150 may include a host and a dopant.

The host may include at least one selected from TPBi, TBADN, ADN (also referred to as “DNA”), CBP, CDBP, and TCP:

In various embodiments, the host may include a compound represented by Formula 301 below: Ar₃₀₁-[(L₃₀₁)_(xb1)-R₃₀₁]_(xb2),  Formula 301

In Formula 301,

-   -   Ar₃₀₁ may be selected from the group consisting of:     -   a naphthalene group, a heptalene group, a fluorene group, a         spiro-fluorene group, a benzofluorene group, a dibenzofluorene         group, a phenalene group, a phenanthrene group, an anthracene         group, a fluoranthene group, a triphenylene group, a pyrene         group, a chrysene group, a naphthacene group, a picene group, a         perylene group, a pentaphene group, and an indenoanthracene         group; and     -   a naphthalene group, a heptalene group, a fluorene group, a         spiro-fluorene group, a benzofluorene group, a dibenzofluorene         group, a phenalene group, a phenanthrene group, an anthracene         group, a fluoranthene group, a triphenylene group, a pyrene         group, a chrysene group, a naphthacene group, a picene group, a         perylene group, a pentaphene group, and an indenoanthracene         group, each substituted with at least one selected from         deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a         nitro group, an amino group, an amidino group, a hydrazine         group, a hydrazone group, a carboxylic acid group or a salt         thereof, a sulfonic acid group or a salt thereof, a phosphoric         acid group or a salt thereof, a C₁-C₆₀ alkyl group, a C₂-C₆₀         alkenyl group, a C₂-C₆₀ alkynyl group, a C₁-C₆₀ alkoxy group, a         C₃-C₁₀ cycloalkyl group, a C₁-C₁₀ heterocycloalkyl group, a         C₃-C₁₀ cycloalkenyl group, a C₁-C₁₀ heterocycloalkenyl group, a         C₆-C₆₀ aryl group, a C₆-C₆₀ aryloxy group, a C₆-C₆₀ arylthio         group, a C₁-C₆₀ heteroaryl group, a monovalent non-aromatic         condensed polycyclic group, a monovalent non-aromatic condensed         heteropolycyclic group, a biphenyl group, a terphenyl group, and         —Si(Q₃₀₁)(Q₃₀₂)(Q₃₀₃) (wherein Q₃₀₁ to Q₃₀₃ may each         independently be selected from hydrogen, a C₁-C₆₀ alkyl group, a         C₂-C₆₀ alkenyl group, a C₆-C₆₀ aryl group, and a C₁-C₆₀         heteroaryl group);     -   L₃₀₁ may be selected from a substituted or unsubstituted C₃-C₁₀         cycloalkylene group, a substituted or unsubstituted C₁-C₁₀         heterocycloalkylene group, a substituted or unsubstituted C₃-C₁₀         cycloalkenylene group, a substituted or unsubstituted C₁-C₁₀         heterocycloalkenylene group, a substituted or unsubstituted         C₆-C₆₀ arylene group, a substituted or unsubstituted C₁-C₆₀         heteroarylene group, a substituted or unsubstituted divalent         non-aromatic condensed polycyclic group, and a substituted or         unsubstituted divalent non-aromatic condensed heteropolycyclic         group,     -   R₃₀₁ may be selected from the group consisting of:     -   a C₁-C₂₀ alkyl group and a C₁-C₂₀ alkoxy group;     -   a C₁-C₂₀ alkyl group and a C₁-C₂₀ alkoxy group, each substituted         with at least one selected from deuterium, —F, —Cl, —Br, —I, a         hydroxyl group, a cyano group, a nitro group, an amino group, an         amidino group, a hydrazine group, a hydrazone group, a         carboxylic acid group or a salt thereof, a sulfonic acid group         or a salt thereof, a phosphoric acid group or a salt thereof, a         phenyl group, a biphenyl group, a terphenyl group, a naphthyl         group, a fluorenyl group, a spiro-fluorenyl group, a         benzofluorenyl group, a dibenzofluorenyl group, a phenanthrenyl         group, an anthracenyl group, a pyrenyl group, a chrysenyl group,         a pyridinyl group, a pyrazinyl group, a pyrimidinyl group, a         pyridazinyl group, a quinolinyl group, an isoquinolinyl group, a         quinoxalinyl group, a quinazolinyl group, a carbazolyl group,         and a triazinyl group;     -   a phenyl group, a biphenyl group, a terphenyl group, a naphthyl         group, a fluorenyl group, a spiro-fluorenyl group, a         benzofluorenyl group, a dibenzofluorenyl group, a phenanthrenyl         group, an anthracenyl group, a pyrenyl group, a chrysenyl group,         a pyridinyl group, a pyrazinyl group, a pyrimidinyl group, a         pyridazinyl group, a quinolinyl group, an isoquinolinyl group, a         quinoxalinyl group, a quinazolinyl group, a carbazole group, and         a triazinyl group; and     -   a phenyl group, a naphthyl group, a fluorenyl group, a         spiro-fluorenyl group, a benzofluorenyl group, a         dibenzofluorenyl group, a phenanthrenyl group, an anthracenyl         group, a pyrenyl group, a chrysenyl group, a pyridinyl group, a         pyrazinyl group, a pyrimidinyl group, a pyridazinyl group, a         quinolinyl group, an isoquinolinyl group, a quinoxalinyl group,         a quinazolinyl group, a carbazole group, and a triazinyl group,         each substituted with at least one selected from deuterium, —F,         —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an         amino group, an amidino group, a hydrazine group, a hydrazone         group, a carboxylic acid group or a salt thereof, a sulfonic         acid group or a salt thereof, a phosphoric acid group or a salt         thereof, a C₁-C₂₀ alkyl group, a C₁-C₂₀ alkoxy group, a phenyl         group, a biphenyl group, a terphenyl group, a naphthyl group, a         fluorenyl group, a spiro-fluorenyl group, a benzofluorenyl         group, a dibenzofluorenyl group, a phenanthrenyl group, an         anthracenyl group, a pyrenyl group, a chrysenyl group, a         pyridinyl group, a pyrazinyl group, a pyrimidinyl group, a         pyridazinyl group, a quinolinyl group, an isoquinolinyl group, a         quinoxalinyl group, a quinazolinyl group, a carbazolyl group,         and a triazinyl group,     -   xb1 may be selected from 0, 1, 2, and 3, and     -   xb2 may be selected from 1, 2, 3, and 4.

For example, in Formula 301,

-   -   L₃₀₁ may be selected from the group consisting of:     -   a phenylene group, a naphthylene group, a fluorenylene group, a         spiro-fluorenylene group, a benzofluorenylene group, a         dibenzofluorenylene group, a phenanthrenylene group, an         anthracenylene group, a pyrenylene group, and a chrysenylene         group; and     -   a phenylene group, a naphthylene group, a fluorenylene group, a         spiro-fluorenylene group, a benzofluorenylene group, a         dibenzofluorenylene group, a phenanthrenylene group, an         anthracenylene group, a pyrenylene group, and a chrysenylene         group, each substituted with at least one selected from         deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a         nitro group, an amino group, an amidino group, a hydrazine         group, a hydrazone group, a carboxylic acid group or a salt         thereof, a sulfonic acid group or a salt thereof, a phosphoric         acid group or a salt thereof, a C₁-C₂₀ alkyl group, a C₁-C₂₀         alkoxy group, a phenyl group, a biphenyl group, a terphenyl         group, a naphthyl group, a fluorenyl group, a spiro-fluorenyl         group, a benzofluorenyl group, a dibenzofluorenyl group, a         phenanthrenyl group, an anthracenyl group, a pyrenyl group, and         a chrysenyl group,     -   R₃₀₁ may be selected from the group consisting of:     -   a C₁-C₂₀ alkyl group and a C₁-C₂₀ alkoxy group;     -   a C₁-C₂₀ alkyl group and a C₁-C₂₀ alkoxy group, each substituted         with at least one selected from deuterium, —F, —Cl, —Br, —I, a         hydroxyl group, a cyano group, a nitro group, an amino group, an         amidino group, a hydrazine group, a hydrazone group, a         carboxylic acid group or a salt thereof, a sulfonic acid group         or a salt thereof, a phosphoric acid group or a salt thereof, a         phenyl group, a biphenyl group, a terphenyl group, a naphthyl         group, a fluorenyl group, a spiro-fluorenyl group, a         benzofluorenyl group, a dibenzofluorenyl group, a phenanthrenyl         group, an anthracenyl group, a pyrenyl group, and a chrysenyl         group;     -   a phenyl group, a biphenyl group, a terphenyl group, a naphthyl         group, a fluorenyl group, a spiro-fluorenyl group, a         benzofluorenyl group, a dibenzofluorenyl group, a phenanthrenyl         group, an anthracenyl group, a pyrenyl group, and a chrysenyl         group; and     -   a phenyl group, a biphenyl group, a terphenyl group, a naphthyl         group, a fluorenyl group, a spiro-fluorenyl group, a         benzofluorenyl group, a dibenzofluorenyl group, a phenanthrenyl         group, an anthracenyl group, a pyrenyl group, and a chrysenyl         group, each substituted with at least one selected from         deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a         nitro group, an amino group, an amidino group, a hydrazine         group, a hydrazone group, a carboxylic acid group or a salt         thereof, a sulfonic acid group or a salt thereof, a phosphoric         acid group or a salt thereof, a C₁-C₂₀ alkyl group, a C₁-C₂₀         alkoxy group, a phenyl group, a biphenyl group, a terphenyl         group, a naphthyl group, a fluorenyl group, a spiro-fluorenyl         group, a benzofluorenyl group, a dibenzofluorenyl group, a         phenanthrenyl group, an anthracenyl group, a pyrenyl group, and         a chrysenyl group, but embodiments of the present disclosure are         not limited thereto.

For example, the host may include a compound represented by Formula 301A below:

The substituents of Formula 301A may be the same as described above.

The compound represented by Formula 301 may include at least one selected from Compounds H1 to H42, but embodiments of the present disclosure are not limited thereto:

In various embodiments, the host may include at least one selected from Compounds H43 to H49 below, but embodiments of the present disclosure are not limited thereto:

The dopant in the emission layer 150 may include at least one selected from a fluorescent dopant and a phosphorescent dopant.

The phosphorescent dopant may include an organometallic complex represented by Formula 401 below:

In Formula 401,

-   -   M may be selected from iridium (Ir), platinum (Pt), osmium (Os),         titanium (Ti), zirconium (Zr), hafnium (Hf), europium (Eu),         terbium (Tb), and thulium (TM),     -   X₄₀₁ to X₄₀₄ may each independently be nitrogen or carbon,     -   rings A₄₀₁ and A₄₀₂ may each independently be selected from a         substituted or unsubstituted benzene, a substituted or         unsubstituted naphthalene, a substituted or unsubstituted         fluorene, a substituted or unsubstituted spiro-fluorene, a         substituted or unsubstituted indene, a substituted or         unsubstituted pyrrole, a substituted or unsubstituted thiophene,         a substituted or unsubstituted furan, a substituted or         unsubstituted imidazole, a substituted or unsubstituted         pyrazole, a substituted or unsubstituted thiazole, a substituted         or unsubstituted isothiazole, a substituted or unsubstituted         oxazole, a substituted or unsubstituted isoxazole, a substituted         or unsubstituted pyridine, a substituted or unsubstituted         pyrazine, a substituted or unsubstituted pyrimidine, a         substituted or unsubstituted pyridazine, a substituted or         unsubstituted quinoline, a substituted or unsubstituted         isoquinoline, a substituted or unsubstituted benzoquinoline, a         substituted or unsubstituted quinoxaline, a substituted or         unsubstituted quinazoline, a substituted or unsubstituted         carbazole, a substituted or unsubstituted benzimidazole, a         substituted or unsubstituted benzofuran, a substituted or         unsubstituted benzothiophene, a substituted or unsubstituted         isobenzothiophene, a substituted or unsubstituted benzoxazole, a         substituted or unsubstituted isobenzoxazole, a substituted or         unsubstituted triazole, a substituted or unsubstituted         oxadiazole, a substituted or unsubstituted triazine, a         substituted or unsubstituted dibenzofuran, and a substituted or         unsubstituted dibenzothiophene,     -   at least one substituent of the substituted benzene, the         substituted naphthalene, the substituted fluorene, the         substituted spiro-fluorene, the substituted indene, the         substituted pyrrole, the substituted thiophene, the substituted         furan, the substituted imidazole, the substituted pyrazole, the         substituted thiazole, the substituted isothiazole, the         substituted oxazole, the substituted isoxazole, the substituted         pyridine, the substituted pyrazine, the substituted pyrimidine,         the substituted pyridazine, the substituted quinoline, the         substituted isoquinoline, the substituted benzoquinoline, the         substituted quinoxaline, the substituted quinazoline, the         substituted carbazole, the substituted benzimidazole, the         substituted benzofuran, the substituted benzothiophene, the         substituted isobenzothiophene, the substituted benzoxazole, the         substituted isobenzoxazole, the substituted triazole, the         substituted oxadiazole, the substituted triazine, the         substituted dibenzofuran, and the substituted dibenzothiophene         may be selected from the group consisting of:     -   deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a         nitro group, an amino group, an amidino group, a hydrazine         group, a hydrazone group, a carboxylic acid group or a salt         thereof, a sulfonic acid group or a salt thereof, a phosphoric         acid group or a salt thereof, a C₁-C₆₀ alkyl group, a C₂-C₆₀         alkenyl group, a C₂-C₆₀ alkynyl group, and a C₁-C₆₀ alkoxy         group;     -   a C₁-C₆₀ alkyl group, a C₂-C₆₀ alkenyl group, a C₂-C₆₀ alkynyl         group, and a C₁-C₆₀ alkoxy group, each substituted with at least         one selected from deuterium, —F, —Cl, —Br, —I, a hydroxyl group,         a cyano group, a nitro group, an amino group, an amidino group,         a hydrazine group, a hydrazone group, a carboxylic acid group or         a salt thereof, a sulfonic acid group or a salt thereof, a         phosphoric acid group or a salt thereof, a C₃-C₁₀ cycloalkyl         group, a C₁-C₁₀ heterocycloalkyl group, a C₃-C₁₀ cycloalkenyl         group, a C₁-C₁₀ heterocycloalkenyl group, a C₆-C₆₀ aryl group, a         C₆-C₆₀ aryloxy group, a C₆-C₆₀ arylthio group, a C₁-C₆₀         heteroaryl group, a monovalent non-aromatic condensed polycyclic         group, a monovalent non-aromatic condensed heteropolycyclic         group, a biphenyl group, a terphenyl group, —N(Q₄₀₁)(Q₄₀₂),         —Si(Q₄₀₃)(Q₄₀₄)(Q₄₀₅), and —B(Q₄₀₆)(Q₄₀₇);     -   a C₃-C₁₀ cycloalkyl group, a C₁-C₁₀ heterocycloalkyl group, a         C₃-C₁₀ cycloalkenyl group, a C₁-C₁₀ heterocycloalkenyl group, a         C₆-C₆₀ aryl group, a C₆-C₆₀ aryloxy group, a C₆-C₆₀ arylthio         group, a C₁-C₆₀ heteroaryl group, a monovalent non-aromatic         condensed polycyclic group, a monovalent non-aromatic condensed         heteropolycyclic group, a biphenyl group, and a terphenyl group;     -   a C₃-C₁₀ cycloalkyl group, a C₁-C₁₀ heterocycloalkyl group, a         C₃-C₁₀ cycloalkenyl group, a C₁-C₁₀ heterocycloalkenyl group, a         C₆-C₆₀ aryl group, a C₆-C₆₀ aryloxy group, a C₆-C₆₀ arylthio         group, a C₁-C₆₀ heteroaryl group, a monovalent non-aromatic         condensed polycyclic group, a monovalent non-aromatic condensed         heteropolycyclic group, a biphenyl group, and a terphenyl group,         each substituted with at least one selected from deuterium, —F,         —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an         amino group, an amidino group, a hydrazine group, a hydrazone         group, a carboxylic acid group or a salt thereof, a sulfonic         acid group or a salt thereof, a phosphoric acid group or a salt         thereof, a C₁-C₆₀ alkyl group, a C₂-C₆₀ alkenyl group, a C₂-C₆₀         alkynyl group, a C₁-C₆₀ alkoxy group, a C₃-C₁₀ cycloalkyl group,         a C₁-C₁₀ heterocycloalkyl group, a C₃-C₁₀ cycloalkenyl group, a         C₁-C₁₀ heterocycloalkenyl group, a C₆-C₆₀ aryl group, a C₆-C₆₀         aryloxy group, a C₆-C₆₀ arylthio group, a C₁-C₆₀ heteroaryl         group, a monovalent non-aromatic condensed polycyclic group, a         monovalent non-aromatic condensed heteropolycyclic group, a         biphenyl group, a terphenyl group, —N(Q₄₁₁)(Q₄₁₂),         —Si(Q₄₁₃)(Q₄₁₄)(Q₄₁₅), and —B(Q₄₁₆)(Q₄₁₇); and     -   —N(Q₄₂₁)(Q₄₂₂), —Si(Q₄₂₃)(Q₄₂₄)(Q₄₂₅), and —B(Q₄₂₆)(Q₄₂₇),     -   L₄₀₁ may be an organic ligand,     -   xc1 may be 1, 2, or 3, and     -   xc2 may be 0, 1, 2, or 3.

L₄₀₁ may be a monovalent, a divalent, or a trivalent organic ligand. For example, L₄₀₁ may be selected from a halogen ligand (for example, Cl or F), a diketone ligand (for example, acetylacetonate, 1,3-diphenyl-1,3-propanedionate, 2,2,6,6-tetramethyl-3,5-heptanedionate, or hexafluoroacetonate), a carboxylic acid ligand (for example, picolinate, dimethyl-3-pyrazolecarboxylate, or benzoate), a carbon monooxide ligand, an isonitrile ligand, a cyano group ligand, and a phosphorus ligand (for example, phosphine or phosphite), but embodiments of the present disclosure are not limited thereto.

Q₄₀₁ to Q₄₀₇, Q₄₁₁ to Q₄₁₇, and Q₄₂₁ to Q₄₂₇ may each independently be selected from hydrogen, a C₁-C₆₀ alkyl group, a C₂-C₆₀ alkenyl group, a C₆-C₆₀ aryl group, and a C₁-C₆₀ heteroaryl group.

When A₄₀₁ in Formula 401 has two or more substituents, the two or more substituents of A₄₀₁ may be connected to form a saturated or unsaturated ring.

When A₄₀₂ in Formula 401 has two or more substituents, the two or more substituents of A₄₀₂ may be connected to form a saturated or unsaturated ring.

When xc1 in Formula 401 is two or more, a plurality of ligands

-   -   in Formula 401 may be identical to or different from one         another. When xc1 in Formula 401 is two or more, A₄₀₁ and A₄₀₂         may be respectively directly connected to A₄₀₁ and A₄₀₂ of other         neighboring ligands with or without a linker (for example, a         C₁-C₅ alkylene, —N(R′)— (wherein R′ may be a C₁-C₁₀ alkyl group         or a C₆-C₂₀ aryl group), or —C(═O)—) therebetween.

The phosphorescent dopant may include at least one selected from Compounds PD1 to PD74 below, but embodiments of the present disclosure are not limited thereto:

In various embodiments, the phosphorescent dopant may include PtOEP:

The fluorescent dopant may include at least one selected from DPAVBi, BDAVBi, TBPe, DCM, DCJTB, Coumarin 6, and C545T:

In various embodiments, the fluorescent dopant may include a compound represented by Formula 501:

In Formula 501,

-   -   Ar₅₀₁ may be selected from the group consisting of:     -   a naphthalene, a heptalene, a fluorene, a spiro-fluorene, a         benzofluorene, a dibenzofluorene, a phenalene, a phenanthrene,         an anthracene, a fluoranthene, a triphenylene, a pyrene, a         chrysene, a naphthacene, a picene, a perylene, a pentaphene, and         an indenoanthracene; and     -   a naphthalene, a heptalene, a fluorene, a spiro-fluorene, a         benzofluorene, a dibenzofluorene, a phenalene, a phenanthrene,         an anthracene, a fluoranthene, a triphenylene, a pyrene, a         chrysene, a naphthacene, a picene, a perylene, a pentaphene, and         an indenoanthracene, each substituted with at least one selected         from deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano         group, a nitro group, an amino group, an amidino group, a         hydrazine group, a hydrazone group, a carboxylic acid group or a         salt thereof, a sulfonic acid group or a salt thereof, a         phosphoric acid group or a salt thereof, a C₁-C₆₀ alkyl group, a         C₂-C₆₀ alkenyl group, a C₂-C₆₀ alkynyl group, a C₁-C₆₀ alkoxy         group, a C₃-C₁₀ cycloalkyl group, a C₁-C₁₀ heterocycloalkyl         group, a C₃-C₁₀ cycloalkenyl group, a C₁-C₁₀ heterocycloalkenyl         group, a C₆-C₆₀ aryl group, a C₆-C₆₀ aryloxy group, a C₆-C₆₀         arylthio group, a C₁-C₆₀ heteroaryl group, a monovalent         non-aromatic condensed polycyclic group, a monovalent         non-aromatic condensed heteropolycyclic group, a biphenyl group,         a terphenyl group, and —Si(Q₅₀₁)(Q₅₀₂)(Q₅₀₃) (wherein Q₅₀₁ to         Q₅₀₃ are each independently selected from hydrogen, a C₁-C₆₀         alkyl group, a C₂-C₆₀ alkenyl group, a C₆-C₆₀ aryl group, and a         C₁-C₆₀ heteroaryl group),     -   L₅₀₁ to L₅₀₃ may each independently be the same as described         herein in connection with L₃₀₁,     -   R₅₀₁ and R₅₀₂ may each independently be selected from the group         consisting of:     -   a phenyl group, a biphenyl group, a terphenyl group, a naphthyl         group, a fluorenyl group, a spiro-fluorenyl group, a         benzofluorenyl group, a dibenzofluorenyl group, a phenanthrenyl         group, an anthracenyl group, a pyrenyl group, a chrysenyl group,         a pyridinyl group, a pyrazinyl group, a pyrimidinyl group, a         pyridazinyl group, a quinolinyl group, an isoquinolinyl group, a         quinoxalinyl group, a quinazolinyl group, a carbazolyl group, a         triazinyl group, a dibenzofuranyl group, and a dibenzothiophenyl         group; and     -   a phenyl group, a biphenyl group, a terphenyl group, a naphthyl         group, a fluorenyl group, a spiro-fluorenyl group, a         benzofluorenyl group, a dibenzofluorenyl group, a phenanthrenyl         group, an anthracenyl group, a pyrenyl group, a chrysenyl group,         a pyridinyl group, a pyrazinyl group, a pyrimidinyl group, a         pyridazinyl group, a quinolinyl group, an isoquinolinyl group, a         quinoxalinyl group, a quinazolinyl group, a carbazolyl group, a         triazinyl group, a dibenzofuranyl group, and a dibenzothiophenyl         group, each substituted with at least one selected from         deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a         nitro group, an amino group, an amidino group, a hydrazine         group, a hydrazone group, a carboxylic acid group or a salt         thereof, a sulfonic acid group or a salt thereof, a phosphoric         acid group or a salt thereof, a C₁-C₂₀ alkyl group, a C₁-C₂₀         alkoxy group, a phenyl group, a biphenyl group, a terphenyl         group, a naphthyl group, a fluorenyl group, a spiro-fluorenyl         group, a benzofluorenyl group, a dibenzofluorenyl group, a         phenanthrenyl group, an anthracenyl group, a pyrenyl group, a         chrysenyl group, a pyridinyl group, a pyrazinyl group, a         pyrimidinyl group, a pyridazinyl group, a quinolinyl group, an         isoquinolinyl group, a quinoxalinyl group, a quinazolinyl group,         a carbazolyl group, a triazinyl group, a dibenzofuranyl group,         and a dibenzothiophenyl group,     -   xd1 to xd3 may each independently be selected from 0, 1, 2, and         3, and     -   xd4 may be selected from 1, 2, 3, and 4.

The fluorescent dopant may include at least one selected from Compounds FD1 to FD9:

An amount of the dopant in the emission layer may be, in general, in a range of about 0.01 to about 15 parts by weight based on 100 parts by weight of the host, but embodiments of the present disclosure are not limited thereto.

A thickness of the emission layer may be in a range of about 100 Å to about 1,000 Å, for example, about 200 Å to about 600 Å. When the thickness of the emission layer is within these ranges, excellent light-emission characteristics may be obtained without a substantial increase in driving voltage.

When the organic light-emitting device 10 is a full-color organic light-emitting device, the emission layer 150 may be patterned into a red emission layer, a green emission layer, or a blue emission layer, according to a sub-pixel. In some embodiments, the emission layer 150 may have a stacked structure including a red emission layer, a green emission layer, and a blue emission layer; or may include a red-light emission material, a green-light emission material, and a blue-light emission material, which are mixed with each other in a single layer, to thereby emit white light.

Then, the electron transport region 170 may be disposed on the emission layer 150.

The electron transport region 170 may include at least one selected from a hole blocking layer, an electron transport layer, and an electron injection layer. The methods of forming the hole blocking layer, the electron transport layer, and the electron injection layer may be substantially the same as the methods utilized to form the hole injection layer.

For example, the electron transport region 170 may have a structure of electron transport layer/electron injection layer or a structure of hole blocking layer/electron transport layer/electron injection layer, wherein layers of each structure are sequentially stacked in a direction away from the emission layer in the stated order, but the structure thereof is not limited thereto.

In various embodiments, the electron transport layer may include at least one compound selected from a compound represented by Formula 601 and a compound represented by Formula 602 illustrated below: Ar₆₀₁-[(L₆₀₁)_(xe1)-E₆₀₁]_(xe2).  Formula 601

In Formula 601,

-   -   Ar₆₀₁ may be selected from the group consisting of:     -   a naphthalene group, a heptalene group, a fluorene group, a         spiro-fluorene group, a benzofluorene group, a dibenzofluorene         group, a phenalene group, a phenanthrene group, an anthracene         group, a fluoranthene group, a triphenylene group, a pyrene         group, a chrysene group, a naphthacene group, a picene group, a         perylene group, a pentaphene group, and an indenoanthracene         group; and     -   a naphthalene group, a heptalene group, a fluorene group, a         spiro-fluorene group, a benzofluorene group, a dibenzofluorene         group, a phenalene group, a phenanthrene group, a anthracene         group, a fluoranthene group, a triphenylene group, a pyrene         group, a chrysene group, a naphthacene group, a picene group, a         perylene group, a pentaphene group, and an indenoanthracene         group, each substituted with at least one selected from         deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a         nitro group, an amino group, an amidino group, a hydrazine         group, a hydrazone group, a carboxylic acid group or a salt         thereof, a sulfonic acid group or a salt thereof, a phosphoric         acid group or a salt thereof, a C₁-C₆₀ alkyl group, a C₂-C₆₀         alkenyl group, a C₂-C₆₀ alkynyl group, a C₁-C₆₀ alkoxy, a C₃-C₁₀         cycloalkyl group, a C₁-C₁₀ heterocycloalkyl group, a C₃-C₁₀         cycloalkenyl group, a C₁-C₁₀ heterocycloalkenyl group, a C₆-C₆₀         aryl group, a C₆-C₆₀ aryloxy, a C₆-C₆₀ arylthio group, a C₁-C₆₀         heteroaryl group, a monovalent non-aromatic condensed polycyclic         group, a monovalent non-aromatic condensed heteropolycyclic         group, a biphenyl group, a terphenyl group, and         —Si(Q₃₀₁)(Q₃₀₂)(Q₃₀₃) (wherein Q₃₀₁ to Q₃₀₃ are each         independently selected from hydrogen, a C₁-C₆₀ alkyl group, a         C₂-C₆₀ alkenyl group, a C₁-C₆₀ aryl group, and a C₁-C₆₀         heteroaryl group),     -   L₆₀₁ is the same as described in connection with L₃₀₁,     -   E₆₀₁ may be selected from the group consisting of:     -   a pyrrolyl group, a thiophenyl group, a furanyl group, an         imidazolyl group, a pyrazolyl group, a thiazolyl group, an         isothiazolyl group, an oxazolyl group, an isoxazolyl group, a         pyridinyl group, a pyrazinyl group, a pyrimidinyl group, a         pyridazinyl group, an isoindolyl group, an indolyl group, an         indazolyl group, a purinyl group, a quinolinyl group, an         isoquinolinyl group, a benzoquinolinyl group, a phthalazinyl         group, a naphthyridinyl group, a quinoxalinyl group, a         quinazolinyl group, a cinnolinyl group, a carbazolyl, a         phenanthridinyl group, an acridinyl group, a phenanthrolinyl         group, a phenazinyl group, a benzimidazolyl, a benzofuranyl         group, a benzothiophenyl group, an isobenzothiazolyl, a         benzoxazolyl group, an isobenzoxazolyl group, a triazolyl group,         a tetrazolyl group, an oxadiazolyl group, a triazinyl group, a         dibenzofuranyl group, a dibenzothiophenyl group, a         benzocarbazolyl group, a dibenzocarbazolyl group, an         imidazopyridinyl group, and an imidazopyrimidinyl group; and     -   a pyrrolyl group, a thiophenyl group, a furanyl group, an         imidazolyl group, a pyrazolyl group, a thiazolyl group, an         isothiazolyl group, an oxazolyl group, an isoxazolyl group, a         pyridinyl group, a pyrazinyl group, a pyrimidinyl group, a         pyridazinyl group, an isoindolyl group, an indolyl group, an         indazolyl group, a purinyl group, a quinolinyl group, an         isoquinolinyl group, a benzoquinolinyl group, a phthalazinyl         group, a naphthyridinyl group, a quinoxalinyl group, a         quinazolinyl group, a cinnolinyl group, a carbazolyl group, a         phenanthridinyl group, an acridinyl group, a phenanthrolinyl         group, a phenazinyl group, a benzimidazolyl group, a         benzofuranyl group, a benzothiophenyl group, an         isobenzothiazolyl group, a benzoxazolyl group, an         isobenzoxazolyl group, a triazolyl group, a tetrazolyl group, an         oxadiazolyl group, a triazinyl group, a dibenzofuranyl group, a         dibenzothiophenyl group, a benzocarbazolyl group, a         dibenzocarbazolyl group, an imidazopyridinyl group, and an         imidazopyrimidinyl group, each substituted with at least one         selected from deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a         cyano group, a nitro group, an amino group, an amidino group, a         hydrazine group, a hydrazone group, a carboxylic acid group or a         salt thereof, a sulfonic acid group or a salt thereof, a         phosphoric acid group or a salt thereof, a C₁-C₂₀ alkyl group, a         C₁-C₂₀ alkoxy group, a phenyl group, a biphenyl group, a         terphenyl group, a pentalenyl group, an indenyl group, a         naphthyl group, an azulenyl group, a heptalenyl group, an         indacenyl group, an acenaphthyl group, a fluorenyl group, a         spiro-fluorenyl group, a benzofluorenyl group, a         dibenzofluorenyl group, a phenalenyl group, a phenanthrenyl         group, an anthracenyl group, a fluoranthenyl group, a         triphenylenyl group, a pyrenyl group, a chrysenyl group, a         naphthacenyl group, a picenyl group, a perylenyl group, a         pentaphenyl group, a hexacenyl group, a pentacenyl group, a         rubicenyl group, a coronenyl group, an ovalenyl group, a         pyrrolyl group, a thiophenyl group, a furanyl group, an         imidazolyl group, a pyrazolyl group, a thiazolyl group, an         isothiazolyl group, an oxazolyl group, an isoxazolyl group, a         pyridinyl group, a pyrazinyl group, a pyrimidinyl group, a         pyridazinyl group, an isoindolyl group, an indolyl group, an         indazolyl group, a purinyl group, a quinolinyl group, an         isoquinolinyl group, a benzoquinolinyl group, a phthalazinyl         group, a naphthyridinyl group, a quinoxalinyl group, a         quinazolinyl group, a cinnolinyl group, a carbazolyl group, a         phenanthridinyl group, an acridinyl group, a phenanthrolinyl         group, a phenazinyl group, a benzimidazolyl group, a         benzofuranyl group, a benzothiophenyl group, an         isobenzothiazolyl group, a benzoxazolyl group, an         isobenzoxazolyl group, a triazolyl group, a tetrazolyl group, an         oxadiazolyl group, a triazinyl group, a dibenzofuranyl group, a         dibenzothiophenyl group, a benzocarbazolyl group, a         dibenzocarbazolyl group, an imidazopyridinyl group, and an         imidazopyrimidinyl group,     -   xe1 may be selected from 0, 1, 2, and 3, and     -   xe2 may be selected from 1, 2, 3, and 4.

In Formula 602,

-   -   X₆₁₁ may be N or C-(L₆₁₁)_(xe611)-R₆₁₁, X₆₁₂ may be N or         C-(L₆₁₂)_(xe612)-R₆₁₂, X₆₁₃ may be N or C-(L₆₁₃)_(xe613)-R₆₁₃,         and at least one selected from X₆₁₁ to X₆₁₃ may be N,     -   L₆₁₁ to L₆₁₆ are the same as described in connection with L₃₀₁,     -   R₆₁₁ to R₆₁₆ may each independently be selected from the group         consisting of:     -   a phenyl group, a biphenyl group, a terphenyl group, a naphthyl         group, a fluorenyl group, a spiro-fluorenyl group, a         benzofluorenyl group, a dibenzofluorenyl group, a phenanthrenyl         group, an anthracenyl group, a pyrenyl group, a chrysenyl group,         a pyridinyl group, a pyrazinyl group, a pyrimidinyl group, a         pyridazinyl group, a quinolinyl group, an isoquinolinyl group, a         quinoxalinyl group, a quinazolinyl group, a carbazolyl group,         and a triazinyl group; and     -   a phenyl group, a naphthyl group, a fluorenyl group, a         spiro-fluorenyl group, a benzofluorenyl group, a         dibenzofluorenyl group, a phenanthrenyl group, an anthracenyl         group, a pyrenyl group, a chrysenyl group, a pyridinyl group, a         pyrazinyl group, a pyrimidinyl group, a pyridazinyl group, a         quinolinyl group, an isoquinolinyl group, a quinoxalinyl group,         a quinazolinyl group, a carbazolyl group, and a triazinyl group,         each substituted with at least one selected from deuterium, —F,         —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an         amino group, an amidino group, a hydrazine group, a hydrazone         group, a carboxylic acid group or a salt thereof, a sulfonic         acid group or a salt thereof, a phosphoric acid group or a salt         thereof, a C₁-C₂₀ alkyl group, a C₁-C₂₀ alkoxy group, a phenyl         group, a naphthyl group, a fluorenyl group, a spiro-fluorenyl         group, a benzofluorenyl group, a dibenzofluorenyl group, a         phenanthrenyl group, an anthracenyl group, a pyrenyl group, a         chrysenyl group, a pyridinyl group, a pyrazinyl group, a         pyrimidinyl group, a pyridazinyl group, a quinolinyl group, an         isoquinolinyl group, a quinoxalinyl group, a quinazolinyl group,         a carbazolyl group, and a triazinyl group, and     -   xe611 to xe616 may each independently be selected from 0, 1, 2,         and 3.

The compound represented by Formula 601 and the compound represented by Formula 602 may each independently be selected from Compounds ET1 to ET15 illustrated below:

In various embodiments, the electron transport layer may further include at least one selected from BCP, Bphen, Alq₃, BAlq, TAZ, and NTAZ.

A thickness of the electron transport layer may be in a range of about 100 Å to about 1,000 Å, for example, about 150 Å to about 500 Å. When the thickness of the electron transport layer is within the ranges described above, the electron transport layer may have satisfactory electron transport characteristics without a substantial increase in driving voltage.

Also, the electron transport layer may further include, in addition to the materials described above, a metal-containing material.

The metal-containing material may include a Li complex. The Li complex may include, for example, Compound ET-D1 (lithium quinolate, LiQ) and/or ET-D2:

The electron transport region may include an electron injection layer that facilitates injection of electrons from the second electrode 190.

The electron injection layer may be formed on the electron transport layer utilizing one or more suitable methods selected from vacuum deposition, spin coating, casting, an LB method, ink-jet printing, laser-printing, and laser-induced thermal imaging. When an electron injection layer is formed by vacuum deposition or spin coating, deposition and coating conditions for the electron injection layer may be substantially the same as described herein in connection with the deposition and coating conditions for the hole injection layer.

The electron injection layer may include at least one selected from LiF, NaCl, CsF, Li₂O, BaO, and LiQ.

A thickness of the electron injection layer may be in a range of about 1 Å to about 100 Å, for example, about 3 Å to about 90 Å. When the thickness of the electron injection layer is within the ranges described above, the electron injection layer may have satisfactory electron injection characteristics without a substantial increase in driving voltage.

The second electrode 190 may be disposed on the electron transport region 170 having the structure described above. The second electrode 190 may be a cathode which is an electron injection electrode, and in this regard, a material for forming the second electrode 190 may be selected from metal, an alloy, an electrically conductive compound, and a mixture thereof, which may have a relatively low work function. Examples of suitable materials for the second electrode 190 are lithium (Li), magnesium (Mg), aluminum (Al), aluminum-lithium (Al—Li), calcium (Ca), magnesium-indium (Mg—In), and/or magnesium-silver (Mg—Ag). In some embodiments, the material for forming the second electrode 190 may be ITO and/or IZO. The second electrode 190 may be a semi-transmissive electrode or a transmissive electrode.

The term “C₁-C₆₀ alkyl group” as used herein refers to a linear or branched aliphatic saturated hydrocarbon monovalent group having 1 to 60 carbon atoms, and non-limiting examples thereof may include a methyl group, an ethyl group, a propyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, a pentyl group, an iso-amyl group, and a hexyl group. The term “C₁-C₆₀ alkylene group” as used herein refers to a divalent group having substantially the same structure as the C₁-C₆₀ alkyl group.

The term “C₁-C₆₀ alkoxy group” as used herein refers to a monovalent group represented by —OA₁₀₁ (wherein A₁₀₁ is a C₁-C₆₀ alkyl group), and non-limiting examples thereof may include a methoxy group, an ethoxy group, and an isopropyloxy group.

The term “C₂-C₆₀ alkenyl group” as used herein refers to a hydrocarbon group having at least one carbon-carbon double bond in the middle or at the terminus of the C₂-C₆₀ alkyl group, and non-limiting examples thereof may include an ethenyl group, a propenyl group, and a butenyl group. The term “C₂-C₆₀ alkenylene group” as used herein refers to a divalent group having substantially the same structure as the C₂-C₆₀ alkenyl group.

The term “C₂-C₆₀ alkynyl group” as used herein refers to a hydrocarbon group having at least one carbon-carbon triple bond in the middle or at the terminus of the C₂-C₆₀ alkyl group, and non-limiting examples thereof may include an ethynyl group and a propynyl group. The term “C₂-C₆₀ alkynylene group” as used herein refers to a divalent group having substantially the same structure as the C₂-C₆₀ alkynyl group.

The term “C₃-C₁₀ cycloalkyl group” as used herein refers to a monovalent saturated hydrocarbon monocyclic group having 3 to 10 carbon atoms, and non-limiting examples thereof may include a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, and a cycloheptyl group. The term “C₃-C₁₀ cycloalkylene group” as used herein refers to a divalent group having substantially the same structure as the C₃-C₁₀ cycloalkyl group.

The term “C₁-C₁₀ heterocycloalkyl group” as used herein refers to a monovalent saturated monocyclic group having at least one heteroatom selected from N, O, Si, P, and S as a ring-forming atom in addition to 1 to 10 carbon atoms, and non-limiting examples thereof may include a tetrahydrofuranyl group and a tetrahydrothiophenyl group. The term “C₁-C₁₀ heterocycloalkylene group” as used herein refers to a divalent group having substantially the same structure as the C₁-C₁₀ heterocycloalkyl group.

The term “C₃-C₁₀ cycloalkenyl group” as used herein refers to a monovalent monocyclic group that has 3 to 10 carbon atoms and at least one carbon-carbon double bond in the ring thereof and does not have aromaticity, and non-limiting examples thereof may include a cyclopentenyl group, a cyclohexenyl group, and a cycloheptenyl group. The term “C₃-C₁₀ cycloalkenylene group” as used herein refers to a divalent group having substantially the same structure as the C₃-C₁₀ cycloalkenyl group.

The term “C₁-C₁₀ heterocycloalkenyl group” as used herein refers to a monovalent monocyclic group that has at least one heteroatom selected from N, O, Si, P, and S as a ring-forming atom in addition to 1 to 10 carbon atoms, and at least one double bond in its ring. Non-limiting examples of the C₁-C₁₀ heterocycloalkenyl group include a 2,3-dihydrofuranyl group and a 2,3-dihydrothiophenyl group. The term “C₁-C₁₀ heterocycloalkenylene group” as used herein refers to a divalent group having substantially the same structure as the C₁-C₁₀ heterocycloalkenyl group.

The term “C₆-C₆₀ aryl group” as used herein refers to a monovalent group having a carbocyclic aromatic system having 6 to 60 carbon atoms, and the term “C₆-C₆₀ arylene group” as used herein refers to a divalent group having a carbocyclic aromatic system having 6 to 60 carbon atoms. Non-limiting examples of the C₆-C₆₀ aryl group may include a phenyl group, a naphthyl group, an anthracenyl group, a phenanthrenyl group, a pyrenyl group, and a chrysenyl group. When the C₆-C₆₀ aryl group and the C₆-C₆₀ arylene group each include two or more rings, the rings may be fused to each other.

The term “C₁-C₆₀ heteroaryl group” as used herein refers to a monovalent group having an aromatic system that has at least one heteroatom selected from N, O, P, and S as a ring-forming atom in addition to 1 to 60 carbon atoms. The term “C₁-C₆₀ heteroarylene group” as used herein refers to a divalent group having a carbocyclic aromatic system that has at least one heteroatom selected from N, O, P, and S as a ring-forming atom in addition to 1 to 60 carbon atoms. Non-limiting examples of the C₁-C₆₀ heteroaryl group may include a pyridinyl group, a pyrimidinyl group, a pyrazinyl group, a pyridazinyl group, a triazinyl group, a quinolinyl group, and an isoquinolinyl group. When the C₁-C₆₀ heteroaryl group and the C₁-C₆₀ heteroarylene group each include two or more rings, the rings may be fused to each other.

The term “C₆-C₆₀ aryloxy group” as used herein may be represented by —OA₁₀₂ (wherein A₁₀₂ is the C₆-C₆₀ aryl group), and a C₆-C₆₀ arylthio group used herein may be represented by —SA₁₀₃ (wherein A₁₀₃ is the C₆-C₆₀ aryl group).

The term “monovalent non-aromatic condensed polycyclic group” as used herein refers to a monovalent group (for example, having 8 to 60 carbon atoms) that has two or more rings condensed to each other, only carbon atoms as ring-forming atoms, and non-aromaticity in the entire molecular structure. Non-limiting examples of the monovalent non-aromatic condensed polycyclic group may include a fluorenyl group. The term “divalent non-aromatic condensed polycyclic group” as used herein refers to a divalent group having substantially the same structure as the monovalent non-aromatic condensed polycyclic group.

The term “monovalent non-aromatic condensed heteropolycyclic group” as used herein refers to a monovalent group (for example, having 1 to 60 carbon atoms) that has two or more rings condensed to each other, has a heteroatom selected from N, O, Si, P, and S in addition to carbon atoms as ring-forming atoms, and has non-aromaticity in the entire molecular structure. Non-limiting examples of the monovalent non-aromatic condensed heteropolycyclic group include a carbazolyl group. The term “divalent non-aromatic condensed heteropolycyclic group” as used herein refers to a divalent group having the same structure as the monovalent non-aromatic condensed heteropolycyclic group.

As used herein, at least one substituent of the substituted C₃-C₁₀ cycloalkylene group, the substituted C₁-C₁₀ heterocycloalkylene group, the substituted C₃-C₁₀ cycloalkenylene group, the substituted C₁-C₁₀ heterocycloalkenylene group, the substituted C₆-C₆₀ arylene group, the substituted C₁-C₆₀ heteroarylene group, the substituted divalent non-aromatic condensed polycyclic group, the substituted divalent non-aromatic condensed heteropolycyclic group, the substituted C₁-C₆₀ alkyl group, the substituted C₂-C₆₀ alkenyl group, the substituted C₂-C₆₀ alkynyl group, the substituted C₁-C₆₀ alkoxy group, the substituted C₃-C₁₀ cycloalkyl group, the substituted C₁-C₁₀ heterocycloalkyl group, the substituted C₃-C₁₀ cycloalkenyl group, the substituted C₁-C₁₀ heterocycloalkenyl group, the substituted C₆-C₆₀ aryl group, the substituted C₆-C₆₀ aryloxy group, the substituted C₆-C₆₀ arylthio group, the substituted C₁-C₆₀ heteroaryl group, the substituted monovalent non-aromatic condensed polycyclic group, and the substituted monovalent non-aromatic condensed heteropolycyclic group may be selected from the group consisting of:

-   -   deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a         nitro group, an amino group, an amidino group, a hydrazine         group, a hydrazone group, a carboxylic acid group or a salt         thereof, a sulfonic acid group or a salt thereof, a phosphoric         acid group or a salt thereof, a C₁-C₆₀ alkyl group, a C₂-C₆₀         alkenyl group, a C₂-C₆₀ alkynyl group, and a C₁-C₆₀ alkoxy         group;     -   a C₁-C₆₀ alkyl group, a C₂-C₆₀ alkenyl group, a C₂-C₆₀ alkynyl         group, and a C₁-C₆₀ alkoxy group, each substituted with at least         one selected from deuterium, —F, —Cl, —Br, —I, a hydroxyl group,         a cyano group, a nitro group, an amino group, an amidino group,         a hydrazine group, a hydrazone group, a carboxylic acid group or         a salt thereof, a sulfonic acid group or a salt thereof, a         phosphoric acid group or a salt thereof, a C₃-C₁₀ cycloalkyl         group, a C₁-C₁₀ heterocycloalkyl group, a C₃-C₁₀ cycloalkenyl         group, a C₁-C₁₀ heterocycloalkenyl group, a C₆-C₆₀ aryl group, a         C₆-C₆₀ aryloxy group, a C₆-C₆₀ arylthio group, a C₁-C₆₀         heteroaryl group, a monovalent non-aromatic condensed polycyclic         group, a monovalent non-aromatic condensed heteropolycyclic         group, a biphenyl group, a terphenyl group, and         —Si(Q₁₁)(Q₁₂)(Q₁₃);     -   a C₃-C₁₀ cycloalkyl group, a C₁-C₁₀ heterocycloalkyl group, a         C₃-C₁₀ cycloalkenyl group, a C₁-C₁₀ heterocycloalkenyl group, a         C₆-C₆₀ aryl group, a C₆-C₆₀ aryloxy group, a C₆-C₆₀ arylthio         group, a C₁-C₆₀ heteroaryl group, a monovalent non-aromatic         condensed polycyclic group, a monovalent non-aromatic condensed         heteropolycyclic group, a biphenyl group, and a terphenyl group;     -   a C₃-C₁₀ cycloalkyl group, a C₁-C₁₀ heterocycloalkyl group, a         C₃-C₁₀ cycloalkenyl group, a C₁-C₁₀ heterocycloalkenyl group, a         C₆-C₆₀ aryl group, a C₆-C₆₀ aryloxy group, a C₆-C₆₀ arylthio         group, a C₁-C₆₀ heteroaryl group, a monovalent non-aromatic         condensed polycyclic group, a monovalent non-aromatic condensed         heteropolycyclic group, a biphenyl group, and a terphenyl group,         each substituted with at least one selected from deuterium, —F,         —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an         amino group, an amidino group, a hydrazine group, a hydrazone         group, a carboxylic acid group or a salt thereof, a sulfonic         acid group or a salt thereof, a phosphoric acid group or a salt         thereof, a C₁-C₆₀ alkyl group, a C₂-C₆₀ alkenyl group, a C₂-C₆₀         alkynyl group, a C₁-C₆₀ alkoxy group, a C₃-C₁₀ cycloalkyl group,         a C₁-C₁₀ heterocycloalkyl group, a C₃-C₁₀ cycloalkenyl group, a         C₁-C₁₀ heterocycloalkenyl group, a C₆-C₆₀ aryl group, a C₆-C₆₀         aryloxy group, a C₆-C₆₀ arylthio group, a C₁-C₆₀ heteroaryl         group, a monovalent non-aromatic condensed polycyclic group, a         monovalent non-aromatic condensed heteropolycyclic group, a         biphenyl group, a terphenyl group, and —Si(Q₂₁)(Q₂₂)(Q₂₃); and     -   —Si(Q₃₁)(Q₃₂)(Q₃₃),     -   wherein Q₁ to Q₃, Q₁₁ to Q₁₃, Q₂₁ to Q₂₃, and Q₃₁ to Q₃₃ may         each independently be selected from hydrogen, deuterium, —F,         —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an         amino group, an amidino group, a hydrazine group, a hydrazone         group, a carboxylic acid group or a salt thereof, a sulfonic         acid group or a salt thereof, a phosphoric acid group or a salt         thereof, a C₁-C₆₀ alkyl group, a C₂-C₆₀ alkenyl group, a C₂-C₆₀         alkynyl group, a C₁-C₆₀ alkoxy group, a C₃-C₁₀ cycloalkyl group,         a C₁-C₁₀ heterocycloalkyl group, a C₃-C₁₀ cycloalkenyl group, a         C₁-C₁₀ heterocycloalkenyl group, a C₆-C₆₀ aryl group, a C₁-C₆₀         heteroaryl group, a monovalent non-aromatic condensed polycyclic         group, a monovalent non-aromatic condensed heteropolycyclic         group, a biphenyl group, and a terphenyl group.

The term “Ph” as used herein represents a phenyl group; the term “Me” as used herein represents a methyl group; the term “Et” as used herein represents an ethyl group; and the term “ter-Bu” or “Bu^(t)” as used herein represents a tert-butyl group.

The term “a biphenyl group” as used herein refers to a monovalent group having two benzenes linked to each other via a single bond; and the term “a terphenyl group” as used herein refers to a monovalent group having three benzenes in which adjacent benzenes are linked to each other via a single bond.

Hereinafter, an organic light-emitting device according to an embodiment of the present disclosure will be described in more detail with reference to the Examples. However, embodiments of the present disclosure are not limited to the Examples.

EXAMPLE Example 1

An anode was prepared by cutting an ITO glass substrate (manufactured by Corning), on which an ITO layer was deposited to have a thickness of 15 Ω/cm² (1,200 Å), to a size of 50 mm×50 mm×0.7 mm, ultrasonically cleaning the ITO glass substrate utilizing isopropyl alcohol for 5 minutes and pure water for 5 minutes each, and then, exposing the ITO glass substrate to irradiation of UV light for 30 minutes and exposing the substrate to ozone. Then, the ITO glass substrate was loaded into a vacuum deposition apparatus.

2-TNATA was vacuum-deposited on the ITO glass substrate to form a hole injection layer having a thickness of 600 Å, and Compound 105 was vacuum-deposited on the hole injection layer to form a hole transport layer having a thickness of 300 Å.

Compound 1 was vacuum-deposited on the hole transport layer to form a hole auxiliary layer having a thickness of 60 Å, thereby forming a hole transport region.

Compound CBP (as a host) and Compound PD2 (as a dopant) were co-deposited on the hole auxiliary layer at a weight ratio of 95:5 to form an emission layer having a thickness of 20 nm.

Compound ET1 was deposited on the emission layer to form an electron transport layer having a thickness of 300 Å, and LiF was deposited on the electron transport layer to form an electron injection layer having a thickness of 10 Å, thereby forming an electron transport region.

Then, Al was deposited on the electron transport region to form a cathode having a thickness of 3,000 Å, thereby completing the manufacture of an organic light-emitting device:

Example 2

An organic light-emitting device was manufactured in substantially the same manner as in Example 1, except that Compound 4 was utilized instead of Compound 1 in forming a hole auxiliary layer.

Example 3

An organic light-emitting device was manufactured in substantially the same manner as in Example 1, except that Compound 7 was utilized instead of Compound 1 in forming a hole auxiliary layer.

Example 4

An organic light-emitting device was manufactured in substantially the same manner as in Example 1, except that Compound 9 was utilized instead of Compound 1 in forming a hole auxiliary layer.

Comparative Example 1

An organic light-emitting device was manufactured in substantially the same manner as in Example 1, except that Compound TPD was utilized instead of Compound 105 in forming a hole transport layer:

Comparative Example 2

An organic light-emitting device was manufactured in substantially the same manner as in Example 1, except that Compound NPB was utilized instead of Compound 1 in forming a hole auxiliary layer:

Comparative Example 3

An organic light-emitting device was manufactured in substantially the same manner as in Example 1, except that Compound TPD was utilized instead of Compound 105 in forming a hole transport layer, and Compound 8 was utilized instead of Compound 1 in forming a hole auxiliary layer.

Comparative Example 4

An organic light-emitting device was manufactured in substantially the same manner as in Example 1, except that Compound TPD was utilized instead of Compound 105 in forming a hole transport layer, and Compound NPB was utilized instead of Compound 1 in forming a hole auxiliary layer.

Comparative Example 5

An organic light-emitting device was manufactured in substantially the same manner as in Example 1, except that a hole auxiliary layer was not formed, and Compound A was utilized instead of Compound 105 in forming a hole transport layer:

Comparative Example 6

An organic light-emitting device was manufactured in substantially the same manner as in Example 1, except that a hole auxiliary layer was not formed, and Compound B was utilized instead of Compound 105 in forming a hole transport layer:

Evaluation Example 1

The driving voltage, current density, efficiency, luminance, emission color, and half lifespan at 1,000 nit of the organic light-emitting devices of Examples 1 to 4 and Comparative Examples 1 to 6 were evaluated utilizing a Keithley SMU 236 and a PR650 luminance measuring meter. Results thereof are shown in Table 1. The half-lifespan is a period of time that lapses until the brightness of the organic light-emitting device was 50% of the initial brightness.

TABLE 1 Material Material for hole for hole Driving Current Half transport auxiliary voltage Density Efficiency Luminance Emission lifespan layer layer (V) (mA/cm²) (cd/A) (cd/m²) color (hr) Example 1 Compound Compound 4.1 11.5 6.8 545 Blue 215 105 1 Example 2 Compound Compound 4.0 10.9 5.3 550 Blue 130 105 4 Example 3 Compound Compound 4.1 11.3 5.1 560 Blue 185 105 7 Example 4 Compound Compound 3.8 16.0 3.7 324 Blue 235 105 9 Comparative TPD Compound 5.2 12.3 4.2 450 Blue 40 Example 1 1 Comparative Compound NPB 4.9 12.0 3.6 393 Blue 72 Example 2 105 Comparative TPD Compound 5.9 9.9 2.7 299 Blue 91 Example 3 8 Comparative TPD NPB 6.5 9.7 3.4 345 Blue 77 Example 4 Comparative Compound — 4.3 10.1 5.1 565 Blue 120 Example 5 A Comparative Compound — 5.0 13.0 2.4 254 Blue 129 Example 6 B

Referring to Table 1, it was confirmed that the organic light-emitting devices of Examples 1 to 4 had low driving voltage, high efficiency, high luminance, and long half lifespan, compared to those of the organic light-emitting devices of Comparative Examples 1 to 6.

An organic light-emitting device according to an embodiment of the present disclosure may have low driving voltage, high efficiency and long lifespan, and may have improved low voltage efficiency.

Expressions such as “at least one of” or “at least one selected from” when preceding a list of elements, modify the entire list of elements and do not modify the individual elements of the list. Further, the use of “may” when describing embodiments of the present invention refers to “one or more embodiments of the present invention.” It will be understood that when an element or layer is referred to as being “on”, “connected to”, “coupled to”, or “adjacent to” another element or layer, it can be directly on, connected to, coupled to, or adjacent to the other element or layer, or one or more intervening elements or layers may be present. In contrast, when an element or layer is referred to as being “directly on,” “directly connected to”, “directly coupled to”, or “immediately adjacent to” another element or layer, there are no intervening elements or layers present. As used herein, the term “substantially,” “about,” and similar terms are used as terms of approximation and not as terms of degree, and are intended to account for the inherent deviations in measured or calculated values that would be recognized by those of ordinary skill in the art. Moreover, any numerical range recited herein is intended to include all sub-ranges of the same numerical precision subsumed within the recited range. For example, a range of “1.0 to 10.0” is intended to include all subranges between (and including) the recited minimum value of 1.0 and the recited maximum value of 10.0, that is, having a minimum value equal to or greater than 1.0 and a maximum value equal to or less than 10.0, such as, for example, 2.4 to 7.6. Any maximum numerical limitation recited herein is intended to include all lower numerical limitations subsumed therein and any minimum numerical limitation recited in this specification is intended to include all higher numerical limitations subsumed therein. Accordingly, Applicant reserves the right to amend this specification, including the claims, to expressly recite any sub-range subsumed within the ranges expressly recited herein.

It should be understood that embodiments described herein should be considered in a descriptive sense only and not for purposes of limitation. Descriptions of features or aspects within each embodiment should typically be considered as available for other similar features or aspects in other embodiments.

While one or more embodiments have been described with reference to the FIGURES, it will be understood by those of ordinary skill in the art that various changes in form and details may be made therein without departing from the spirit and scope as defined by the following claims, and equivalents thereof. 

What is claimed is:
 1. An organic light-emitting device comprising: a first electrode; a second electrode; an emission layer between the first electrode and the second electrode; and a hole transport region between the first electrode and the emission layer, wherein the hole transport region comprises a first compound represented by Formula 1 and a second compound represented by Formula 2:

wherein, in Formulae 1 and 2, X₁ and X₂ are each independently selected from N, B, and P, L₁ to L₆ are each independently selected from a substituted or unsubstituted C₃-C₁₀ cycloalkylene group, a substituted or unsubstituted C₃-C₁₀ cycloalkenylene group, a substituted or unsubstituted C₆-C₆₀ arylene group, and a substituted or unsubstituted divalent non-aromatic condensed polycyclic group, a1 to a6 are each independently an integer selected from 0 to 3, Ar₁ is selected from a substituted or unsubstituted C₃-C₁₀ cycloalkyl group, a substituted or unsubstituted C₁-C₁₀ heterocycloalkyl group, a substituted or unsubstituted C₃-C₁₀ cycloalkenyl group, a substituted or unsubstituted C₁-C₁₀ heterocycloalkenyl group, a substituted or unsubstituted C6-C60 aryl group, a substituted or unsubstituted C₁-C₆₀ heteroaryl group, a substituted or unsubstituted monovalent non-aromatic condensed polycyclic group, and a substituted or unsubstituted monovalent non-aromatic condensed heteropolycyclic group, c1 to c3 are each independently an integer selected from 0 to 3, and a sum of c1, c2, and c3 is one or more, in Formulae 1 and 2, R₁ to R₁₁ are each independently selected from hydrogen, deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amino group, an amidino group, a hydrazine group, a hydrazone group, a carboxylic acid group or a salt thereof, a sulfonic acid group or a salt thereof, a phosphoric acid group or a salt thereof, a substituted or unsubstituted C₁-C₆₀ alkyl group, a substituted or unsubstituted C₂-C₆₀ alkenyl group, a substituted or unsubstituted C₂-C₆₀ alkynyl group, a substituted or unsubstituted C₁-C₆₀ alkoxy group, a substituted or unsubstituted C₃-C₁₀ cycloalkyl group, a substituted or unsubstituted C₁-C₁₀ heterocycloalkyl group, a substituted or unsubstituted C3-C₁₀ cycloalkenyl group, a substituted or unsubstituted C₁-C₁₀ heterocycloalkenyl group, a substituted or unsubstituted C₆-C₆₀ aryl group, a substituted or unsubstituted C₆-C₆₀ aryloxy group, a substituted or unsubstituted C₆-C₆₀ arylthio group, a substituted or unsubstituted C₁-C₆₀ heteroaryl group, a substituted or unsubstituted monovalent non-aromatic condensed polycyclic group, a substituted or unsubstituted monovalent non-aromatic condensed heteropolycyclic group, and —Si(Q₁)(Q₂)(Q₃), b1 and b4 are each independently an integer selected from 1 to 4, b2, and b3 are each independently an integer selected from 1 to 3, b5 to b7 are each independently an integer selected from 1 to 5, R₁₂ to R₁₅ are each independently selected from a substituted or unsubstituted C₁-C₆₀ alkyl group, a substituted or unsubstituted C₃-C₁₀ cycloalkyl group, a substituted or unsubstituted C₁-C₁₀ heterocycloalkyl group, a substituted or unsubstituted C₃-C₁₀ cycloalkenyl group, a substituted or unsubstituted C₁-C₁₀ heterocycloalkenyl group, a substituted or unsubstituted C₆-C₆₀ aryl group, a substituted or unsubstituted C₁-C₆₀ heteroaryl group, a substituted or unsubstituted monovalent non-aromatic condensed polycyclic group, and a substituted or unsubstituted monovalent non-aromatic condensed heteropolycyclic group, and at least one substituent of the substituted C₃-C₁₀ cycloalkylene group, the substituted C₃-C₁₀ cycloalkenylene group, the substituted C₆-C₆₀ arylene group, the substituted divalent non-aromatic condensed polycyclic group, the substituted C₁-C₆₀ alkyl group, the substituted C₂-C₆₀ alkenyl group, the substituted C₂-C₆₀ alkynyl group, the substituted C₁-C₆₀ alkoxy group, the substituted C₃-C₁₀ cycloalkyl group, the substituted C₁-C₁₀ heterocycloalkyl group, the substituted C₃-C₁₀ cycloalkenyl group, the substituted C₁-C₁₀ heterocycloalkenyl group, the substituted C₆-C₆₀ aryl group, the substituted C₆-C₆₀ aryloxy group, the substituted C₆-C₆₀ arylthio group, the substituted C₁-C₆₀ heteroaryl group, the substituted monovalent non-aromatic condensed polycyclic group, and the substituted monovalent non-aromatic condensed heteropolycyclic group is selected from the group consisting of: deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amino group, an amidino group, a hydrazine group, a hydrazone group, a carboxylic acid group or a salt thereof, a sulfonic acid group or a salt thereof, a phosphoric acid group or a salt thereof, a C₁-C₆₀ alkyl group, a C₂-C₆₀ alkenyl group, a C₂-C₆₀ alkynyl group, and a C₁-C₆₀ alkoxy group; a C₁-C₆₀ alkyl group, a C₂-C₆₀ alkenyl group, a C₂-C₆₀ alkynyl group, and a C₁-C₆₀ alkoxy group, each substituted with at least one selected from deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amino group, an amidino group, a hydrazine group, a hydrazone group, a carboxylic acid group or a salt thereof, a sulfonic acid group or a salt thereof, a phosphoric acid group or a salt thereof, a C₃-C₁₀ cycloalkyl group, a C₁-C₁₀ heterocycloalkyl group, a C₃-C₁₀ cycloalkenyl group, a C₁-C₁₀ heterocycloalkenyl group, a C₆-C₆₀ aryl group, a C₆-C₆₀ aryloxy group, a C₆-C₆₀ arylthio group, a C₁-C₆₀ heteroaryl group, a monovalent non-aromatic condensed polycyclic group, a monovalent non-aromatic condensed heteropolycyclic group, a biphenyl group, a terphenyl group, and —Si(Q₁₁)(Q₁₂)(Q₁₃); a C₃-C₁₀ cycloalkyl group, a C₁-C₁₀ heterocycloalkyl group, a C₃-C₁₀ cycloalkenyl group, a C₁-C₁₀ heterocycloalkenyl group, a C₆-C₆₀ aryl group, a C₆-C₆₀ aryloxy group, a C₆-C₆₀ arylthio group, a C₁-C₆₀ heteroaryl group, a monovalent non-aromatic condensed polycyclic group, a monovalent non-aromatic condensed heteropolycyclic group, a biphenyl group, and a terphenyl group; a C₃-C₁₀ cycloalkyl group, a C₁-C₁₀ heterocycloalkyl group, a C₃-C₁₀ cycloalkenyl group, a C₁-C₁₀ heterocycloalkenyl group, a C₆-C₆₀ aryl group, a C₆-C₆₀ aryloxy group, a C₆-C₆₀ arylthio group, a C₁-C₆₀ heteroaryl group, a monovalent non-aromatic condensed polycyclic group, and a monovalent non-aromatic condensed heteropolycyclic group, each substituted with at least one selected from deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amino group, an amidino group, a hydrazine group, a hydrazone group, a carboxylic acid group or a salt thereof, a sulfonic acid group or a salt thereof, a phosphoric acid group or a salt thereof, a C₁-C₆₀ alkyl group, a C₂-C₆₀ alkenyl group, a C₂-C₆₀ alkynyl group, a C₁-C₆₀ alkoxy group, a C₃-C₁₀ cycloalkyl group, a C₁-C₁₀ heterocycloalkyl group, a C₃-C₁₀ cycloalkenyl group, a C₁-C₁₀ heterocycloalkenyl group, a C₆-C₆₀ aryl group, a C₆-C₆₀ aryloxy group, a C₆-C₆₀ arylthio group, a C₁-C₆₀ heteroaryl group, a monovalent non-aromatic condensed polycyclic group, a monovalent non-aromatic condensed heteropolycyclic group, a biphenyl group, a terphenyl group, and —Si(Q₂₁)(Q₂₂)(Q₂₃); and —Si(Q₃₁)(Q₃₂)(Q₃₃), wherein Q₁ to Q₃, Q₁₁ to Q₁₃, Q₂₁ to Q₂₃, and Q₃₁ to Q₃₃ are each independently selected from hydrogen, deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amino group, an amidino group, a hydrazine group, a hydrazone group, a carboxylic acid group or a salt thereof, a sulfonic acid group or a salt thereof, a phosphoric acid group or a salt thereof, a C₁-C₆₀ alkyl group, a C₂-C₆₀ alkenyl group, a C₂-C₆₀ alkynyl group, a C₁-C₆₀ alkoxy group, a C₃-C₁₀ cycloalkyl group, a C₁-C₁₀ heterocycloalkyl group, a C₃-C₁₀ cycloalkenyl group, a C₁-C₁₀ heterocycloalkenyl group, a C₆-C₆₀ aryl group, a C₁-C₆₀ heteroaryl group, a monovalent non-aromatic condensed polycyclic group, a monovalent non-aromatic condensed heteropolycyclic group, a biphenyl group, and a terphenyl group, and * indicates a binding site to a neighboring atom, and wherein X₁₁ to X₁₃ in Formula 2 are each independently selected from groups represented by Formulae 2A(5) to 2A(7) and 2B(2):

in Formulae 2A(5) to 2A(7) and 2B(2), R_(8b) to R_(11b) are each independently selected from a substituted or unsubstituted C₁-C₆₀ alkyl group, a substituted or unsubstituted C₃-C₁₀ cycloalkyl group, a substituted or unsubstituted C₁-C₁₀ heterocycloalkyl group, a substituted or unsubstituted C₃-C₁₀ cycloalkenyl group, a substituted or unsubstituted C₁-C₁₀ heterocycloalkenyl group, a substituted or unsubstituted C₆-C₆₀ aryl group, a substituted or unsubstituted C₁-C₆₀ heteroaryl group, a substituted or unsubstituted monovalent non-aromatic condensed polycyclic group, and a substituted or unsubstituted monovalent non-aromatic condensed heteropolycyclic group; b8b is 1 or 2, b9b to b11b are each independently an integer selected from 1 to 3, and * is a binding site to a neighboring atom.
 2. The organic light-emitting device of claim 1, wherein L₁ to L₆ are each independently selected from the group consisting of: a phenylene group, a pentalenylene group, an indenylene group, a naphthylene group, an azulenylene group, a heptalenylene group, an indacenylene group, an acenaphthylene group, a fluorenylene group, a spiro-fluorenylene group, a benzofluorenylene group, a dibenzofluorenylene group, a phenalenylene group, a phenanthrenylene group, an anthracenylene group, a fluoranthenylene group, a triphenylenylene group, a pyrenylene group, a chrysenylene group, a naphthacenylene group, a picenylene group, a perylenylene group, a pentaphenylene group, a hexacenylene group, a pentacenylene group, a rubicenylene group, a coronenylene group, and an ovalenylene group; and a phenylene group, a pentalenylene group, an indenylene group, a naphthylene group, an azulenylene group, a heptalenylene group, an indacenylene group, an acenaphthylene group, a fluorenylene group, a spiro-fluorenylene group, a benzofluorenylene group, a dibenzofluorenylene group, a phenalenylene group, a phenanthrenylene group, an anthracenylene group, a fluoranthenylene group, a triphenylenylene group, a pyrenylene group, a chrysenylene group, a naphthacenylene group, a picenylene group, a perylenylene group, a pentaphenylene group, a hexacenylene group, a pentacenylene group, a rubicenylene group, a coronenylene group, and an ovalenylene group, each substituted with at least one selected from deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amino group, an am idino group, a hydrazine group, a hydrazone group, a carboxylic acid group or a salt thereof, a sulfonic acid group or a salt thereof, a phosphoric acid group or a salt thereof, a C₁-C₂₀ alkyl group, a C₁-C₂₀ alkoxy group, a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, a cyclopentenyl group, a cyclohexenyl group, a phenyl group, a biphenyl group, a terphenyl group, a pentalenyl group, an indenyl group, a naphthyl group, an azulenyl group, a heptalenyl group, an indacenyl group, an acenaphthyl group, a fluorenyl group, a spiro-fluorenyl group, a benzofluorenyl group, a dibenzofluorenyl group, a phenalenyl group, a phenanthrenyl group, an anthracenyl group, a fluoranthenyl group, a triphenylenyl group, a pyrenyl group, a chrysenyl group, a naphthacenyl group, a picenyl group, a perylenyl group, a pentaphenyl group, a hexacenyl group, a pentacenyl group, a rubicenyl group, a coronenyl group, and an ovalenyl group.
 3. The organic light-emitting device of claim 1, wherein L₁ to L₆ are each independently selected from groups represented by Formulae 3-1 to 3-11:

wherein, in Formulae 3-1 to 3-11, Y₁ is C(Z₃)(Z₄), Z₁ to Z₄ are each independently selected from hydrogen, deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amino group, an amidino group, a hydrazine group, a hydrazone group, a carboxylic acid group or a salt thereof, a sulfonic acid group or a salt thereof, a phosphoric acid group or a salt thereof, a C₁-C₂₀ alkyl group, a C₁-C₂₀ alkoxy group, a phenyl group, a biphenyl group, a terphenyl group, a naphthyl group, a fluorenyl group, a spiro-fluorenyl group, a benzofluorenyl group, a dibenzofluorenyl group, a phenanthrenyl group, an anthracenyl group, a pyrenyl group, and a chrysenyl group, d1 is an integer selected from 1, 2, 3, and 4, d2 is an integer selected from 1, 2, and 3, d3 is an integer selected from 1, 2, 3, 4, 5, and 6, d4 is an integer selected from 1, 2, 3, 4, 5, 6, 7, and 8, d5 is an integer selected from 1, 2, 3, 4, and 5, and * and *′ indicate binding sites to a neighboring atom.
 4. The organic light-emitting device of claim 1, wherein in Formula 1, a1=1, a2=0, and a3=0; a1=0, a2=1, and a3=0; or a1=0, a2=0, and a3=1.
 5. The organic light-emitting device of claim 1, wherein in Formula 2, a4=a5=a6=1; a4=1, a5=1, and a6=0; a4=0, a5=1, and a6=1; or a4=1, a5=0, and a6=1.
 6. The organic light-emitting device of claim 1, wherein Ar₁ is selected from the group consisting of: a phenyl group, a biphenyl group, a terphenyl group, a naphthyl group, a fluorenyl group, a spiro-fluorenyl group, a benzofluorenyl group, a dibenzofluorenyl group, a phenanthrenyl group, an anthracenyl group, a triphenylenyl group, a pyrenyl group, a chrysenyl group, a pyrrolyl group, a thiophenyl group, a furanyl group, an imidazolyl group, a pyrazolyl group, a thiazolyl group, an isothiazolyl group, an oxazolyl group, an isoxazolyl group, a pyridinyl group, a pyrazinyl group, a pyrimidinyl group, a pyridazinyl group, a quinolinyl group, an isoquinolinyl group, a benzoquinolinyl group, a quinoxalinyl group, a quinazolinyl group, a carbazolyl group, a benzimidazolyl group, a benzofuranyl group, a benzothiophenyl group, an isobenzothiazolyl group, a benzoxazolyl group, an isobenzoxazolyl group, an oxadiazolyl group, a triazinyl group, a dibenzofuranyl group, a dibenzothiophenyl group, an imidazopyridinyl group, and an imidazopyrimidinyl group; and a phenyl group, a biphenyl group, a terphenyl group, a naphthyl group, a fluorenyl group, a spiro-fluorenyl group, a benzofluorenyl group, a dibenzofluorenyl group, a phenanthrenyl group, an anthracenyl group, a triphenylenyl group, a pyrenyl group, a chrysenyl group, a pyrrolyl group, a thiophenyl group, a furanyl group, an imidazolyl group, a pyrazolyl group, a thiazolyl group, an isothiazolyl group, an oxazolyl group, an isoxazolyl group, a pyridinyl group, a pyrazinyl group, a pyrimidinyl group, a pyridazinyl group, a quinolinyl group, an isoquinolinyl group, a benzoquinolinyl group, a quinoxalinyl group, a quinazolinyl group, a carbazolyl group, a benzimidazolyl group, a benzofuranyl group, a benzothiophenyl group, an isobenzothiazolyl group, a benzoxazolyl group, an isobenzoxazolyl group, an oxadiazolyl group, a triazinyl group, a dibenzofuranyl group, a dibenzothiophenyl group, an imidazopyridinyl group, and an imidazopyrimidinyl group, each substituted with at least one selected from deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amino group, an amidino group, a hydrazine group, a hydrazone group, a carboxylic acid group or a salt thereof, a sulfonic acid group or a salt thereof, a phosphoric acid group or a salt thereof, a C₁-C₁₀ alkyl group, a C₁-C₁₀ alkoxy group, a phenyl group, a biphenyl group, a terphenyl group, a naphthyl group, a fluorenyl group, a spiro-fluorenyl group, a benzofluorenyl group, a dibenzofluorenyl group, a phenanthrenyl group, an anthracenyl group, a triphenylenyl group, a pyrenyl group, a chrysenyl group, a pyrrolyl group, a thiophenyl group, a furanyl group, an imidazolyl group, a pyrazolyl group, a thiazolyl group, an isothiazolyl group, an oxazolyl group, an isoxazolyl group, a pyridinyl group, a pyrazinyl group, a pyrimidinyl group, a pyridazinyl group, a quinolinyl group, an isoquinolinyl group, a benzoquinolinyl group, a quinoxalinyl group, a quinazolinyl group, a carbazolyl group, a benzimidazolyl group, a benzofuranyl group, a benzothiophenyl group, an isobenzothiazolyl group, a benzoxazolyl group, an isobenzoxazolyl group, an oxadiazolyl group, a triazinyl group, a dibenzofuranyl group, a dibenzothiophenyl group, an imidazopyridinyl group, an imidazopyrimidinyl group, and —Si(Q₃₁)(Q₃₂)(Q₃₃), wherein Q₃₁ to Q₃₃ are each independently selected from a C₁-C₁₀ alkyl group, a C₁-C₁₀ alkoxy group, a phenyl group, and a naphthyl group.
 7. The organic light-emitting device of claim 1, wherein R₁ to R₄ and R₈ to R₁₁ are each independently selected from the group consisting of: hydrogen, deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amino group, an amidino group, a hydrazine group, a hydrazone group, a carboxylic acid group or a salt thereof, a sulfonic acid group or a salt thereof, a phosphoric acid group or a salt thereof, a C₁-C₂₀ alkyl group, and a C₁-C₂₀ alkoxy group; a phenyl group, a biphenyl group, a terphenyl group, a naphthyl group, a fluorenyl group, a spiro-fluorenyl group, a benzofluorenyl group, a dibenzofluorenyl group, a phenanthrenyl group, an anthracenyl group, a triphenylenyl group, a pyrenyl group, a chrysenyl group, a pyrrolyl group, a thiophenyl group, a furanyl group, an imidazolyl group, a pyrazolyl group, a thiazolyl group, an isothiazolyl group, an oxazolyl group, an isoxazolyl group, a pyridinyl group, a pyrazinyl group, a pyrimidinyl group, a pyridazinyl group, a quinolinyl group, an isoquinolinyl group, a benzoquinolinyl group, a quinoxalinyl group, a quinazolinyl group, a carbazolyl group, a benzimidazolyl group, a benzofuranyl group, a benzothiophenyl group, an isobenzothiazolyl group, a benzoxazolyl group, an isobenzoxazolyl group, an oxadiazolyl group, a triazinyl group, a dibenzofuranyl group, a dibenzothiophenyl group, an imidazopyridinyl group, and an imidazopyrimidinyl group; a phenyl group, a biphenyl group, a terphenyl group, a naphthyl group, a fluorenyl group, a spiro-fluorenyl group, a benzofluorenyl group, a dibenzofluorenyl group, a phenanthrenyl group, an anthracenyl group, a triphenylenyl group, a pyrenyl group, a chrysenyl group, a pyrrolyl group, a thiophenyl group, a furanyl group, an imidazolyl group, a pyrazolyl group, a thiazolyl group, an isothiazolyl group, an oxazolyl group, an isoxazolyl group, a pyridinyl group, a pyrazinyl group, a pyrimidinyl group, a pyridazinyl group, a quinolinyl group, an isoquinolinyl group, a benzoquinolinyl group, a quinoxalinyl group, a quinazolinyl group, a carbazolyl group, a benzimidazolyl group, a benzofuranyl group, a benzothiophenyl group, an isobenzothiazolyl group, a benzoxazolyl group, an isobenzoxazolyl group, an oxadiazolyl group, a triazinyl group, a dibenzofuranyl group, a dibenzothiophenyl group, an imidazopyridinyl group, and an imidazopyrimidinyl group, each substituted with at least one selected from deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amino group, an amidino group, a hydrazine group, a hydrazone group, a carboxylic acid group or a salt thereof, a sulfonic acid group or a salt thereof, a phosphoric acid group or a salt thereof, a C₁-C₁₀ alkyl group, a C₁-C₁₀ alkoxy group, a phenyl group, a biphenyl group, a terphenyl group, a naphthyl group, a fluorenyl group, a spiro-fluorenyl group, a benzofluorenyl group, a dibenzofluorenyl group, a phenanthrenyl group, an anthracenyl group, a triphenylenyl group, a pyrenyl group, a chrysenyl group, a pyrrolyl group, a thiophenyl group, a furanyl group, an imidazolyl group, a pyrazolyl group, a thiazolyl group, an isothiazolyl group, an oxazolyl group, an isoxazolyl group, a pyridinyl group, a pyrazinyl group, a pyrimidinyl group, a pyridazinyl group, a quinolinyl group, an isoquinolinyl group, a benzoquinolinyl group, a quinoxalinyl group, a quinazolinyl group, a carbazolyl group, a benzimidazolyl group, a benzofuranyl group, a benzothiophenyl group, an isobenzothiazolyl group, a benzoxazolyl group, an isobenzoxazolyl group, an oxadiazolyl group, a triazinyl group, a dibenzofuranyl group, a dibenzothiophenyl group, an imidazopyridinyl group, an imidazopyrimidinyl group, and —Si(Q₃₁)(Q₃₂)(Q₃₃); and —Si(Q₁)(Q₂)(Q₃), R₅ to R₇ are each independently selected from the group consisting of: hydrogen, deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amino group, an am idino group, a hydrazine group, a hydrazone group, a carboxylic acid group or a salt thereof, a sulfonic acid group or a salt thereof, a phosphoric acid group or a salt thereof, a C₁-C₂₀ alkyl group, and a C₁-C₂₀ alkoxy group; a phenyl group, a biphenyl group, a terphenyl group, a naphthyl group, a spiro-fluorenyl group, a benzofluorenyl group, a dibenzofluorenyl group, a phenanthrenyl group, an anthracenyl group, a triphenylenyl group, a pyrenyl group, a chrysenyl group, a pyrrolyl group, a thiophenyl group, a furanyl group, an imidazolyl group, a pyrazolyl group, a thiazolyl group, an isothiazolyl group, an oxazolyl group, an isoxazolyl group, a pyridinyl group, a pyrazinyl group, a pyrimidinyl group, a pyridazinyl group, a quinolinyl group, an isoquinolinyl group, a benzoquinolinyl group, a quinoxalinyl group, a quinazolinyl group, a carbazolyl group, a benzimidazolyl group, a benzofuranyl group, a benzothiophenyl group, an isobenzothiazolyl group, a benzoxazolyl group, an isobenzoxazolyl group, an oxadiazolyl group, a triazinyl group, a dibenzofuranyl group, a dibenzothiophenyl group, an imidazopyridinyl group, and an imidazopyrimidinyl group; a phenyl group, a biphenyl group, a terphenyl group, a naphthyl group, a spiro-fluorenyl group, a benzofluorenyl group, a dibenzofluorenyl group, a phenanthrenyl group, an anthracenyl group, a triphenylenyl group, a pyrenyl group, a chrysenyl group, a pyrrolyl group, a thiophenyl group, a furanyl group, an imidazolyl group, a pyrazolyl group, a thiazolyl group, an isothiazolyl group, an oxazolyl group, an isoxazolyl group, a pyridinyl group, a pyrazinyl group, a pyrimidinyl group, a pyridazinyl group, a quinolinyl group, an isoquinolinyl group, a benzoquinolinyl group, a quinoxalinyl group, a quinazolinyl group, a carbazolyl group, a benzimidazolyl group, a benzofuranyl group, a benzothiophenyl group, an isobenzothiazolyl group, a benzoxazolyl group, an isobenzoxazolyl group, an oxadiazolyl group, a triazinyl group, a dibenzofuranyl group, a dibenzothiophenyl group, an imidazopyridinyl group, and an imidazopyrimidinyl group, each substituted with at least one selected from deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amino group, an amidino group, a hydrazine group, a hydrazone group, a carboxylic acid group or a salt thereof, a sulfonic acid group or a salt thereof, a phosphoric acid group or a salt thereof, a C₁-C₁₀ alkyl group, a C₁-C₁₀ alkoxy group, a phenyl group, a biphenyl group, a terphenyl group, a naphthyl group, a spiro-fluorenyl group, a benzofluorenyl group, a dibenzofluorenyl group, a phenanthrenyl group, an anthracenyl group, a triphenylenyl group, a pyrenyl group, a chrysenyl group, a pyrrolyl group, a thiophenyl group, a furanyl group, an imidazolyl group, a pyrazolyl group, a thiazolyl group, an isothiazolyl group, an oxazolyl group, an isoxazolyl group, a pyridinyl group, a pyrazinyl group, a pyrimidinyl group, a pyridazinyl group, a quinolinyl group, an isoquinolinyl group, a benzoquinolinyl group, a quinoxalinyl group, a quinazolinyl group, a carbazolyl group, a benzimidazolyl group, a benzofuranyl group, a benzothiophenyl group, an isobenzothiazolyl group, a benzoxazolyl group, an isobenzoxazolyl group, an oxadiazolyl group, a triazinyl group, a dibenzofuranyl group, a dibenzothiophenyl group, an imidazopyridinyl group, an imidazopyrimidinyl group, and —Si(Q₃₁)(Q₃₂)(Q₃₃); and —Si(Q₁)(Q₂)(Q₃), and R₁₂ to R₁₅ are each independently selected from the group consisting of: a C₁-C₂₀ alkyl group and a C₁-C₂₀ alkoxy group; a phenyl group, a biphenyl group, a terphenyl group, a naphthyl group, a fluorenyl group, a spiro-fluorenyl group, a benzofluorenyl group, a dibenzofluorenyl group, a phenanthrenyl group, an anthracenyl group, a triphenylenyl group, a pyrenyl group, a chrysenyl group, a pyrrolyl group, a thiophenyl group, a furanyl group, an imidazolyl group, a pyrazolyl group, a thiazolyl group, an isothiazolyl group, an oxazolyl group, an isoxazolyl group, a pyridinyl group, a pyrazinyl group, a pyrimidinyl group, a pyridazinyl group, a quinolinyl group, an isoquinolinyl group, a benzoquinolinyl group, a quinoxalinyl group, a quinazolinyl group, a carbazolyl group, a benzimidazolyl group, a benzofuranyl group, a benzothiophenyl group, an isobenzothiazolyl group, a benzoxazolyl group, an isobenzoxazolyl group, an oxadiazolyl group, a triazinyl group, a dibenzofuranyl group, a dibenzothiophenyl group, an imidazopyridinyl group, and an imidazopyrimidinyl group; a phenyl group, a biphenyl group, a terphenyl group, a naphthyl group, a fluorenyl group, a spiro-fluorenyl group, a benzofluorenyl group, a dibenzofluorenyl group, a phenanthrenyl group, an anthracenyl group, a triphenylenyl group, a pyrenyl group, a chrysenyl group, a pyrrolyl group, a thiophenyl group, a furanyl group, an imidazolyl group, a pyrazolyl group, a thiazolyl group, an isothiazolyl group, an oxazolyl group, an isoxazolyl group, a pyridinyl group, a pyrazinyl group, a pyrimidinyl group, a pyridazinyl group, a quinolinyl group, an isoquinolinyl group, a benzoquinolinyl group, a quinoxalinyl group, a quinazolinyl group, a carbazolyl group, a benzimidazolyl group, a benzofuranyl group, a benzothiophenyl group, an isobenzothiazolyl group, a benzoxazolyl group, an isobenzoxazolyl group, an oxadiazolyl group, a triazinyl group, a dibenzofuranyl group, a dibenzothiophenyl group, an imidazopyridinyl group, and an imidazopyrimidinyl group, each substituted with at least one selected from deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amino group, an amidino group, a hydrazine group, a hydrazone group, a carboxylic acid group or a salt thereof, a sulfonic acid group or a salt thereof, a phosphoric acid group or a salt thereof, a C₁-C₁₀ alkyl group, a C₁-C₁₀ alkoxy group, a phenyl group, a biphenyl group, a terphenyl group, a naphthyl group, a fluorenyl group, a spiro-fluorenyl group, a benzofluorenyl group, a dibenzofluorenyl group, a phenanthrenyl group, an anthracenyl group, a triphenylenyl group, a pyrenyl group, a chrysenyl group, a pyrrolyl group, a thiophenyl group, a furanyl group, an imidazolyl group, a pyrazolyl group, a thiazolyl group, an isothiazolyl group, an oxazolyl group, an isoxazolyl group, a pyridinyl group, a pyrazinyl group, a pyrimidinyl group, a pyridazinyl group, a quinolinyl group, an isoquinolinyl group, a benzoquinolinyl group, a quinoxalinyl group, a quinazolinyl group, a carbazolyl group, a benzimidazolyl group, a benzofuranyl group, a benzothiophenyl group, an isobenzothiazolyl group, a benzoxazolyl group, an isobenzoxazolyl group, an oxadiazolyl group, a triazinyl group, a dibenzofuranyl group, a dibenzothiophenyl group, an imidazopyridinyl group, an imidazopyrimidinyl group, and —Si(Q₃₁)(Q₃₂)(Q₃₃); and —Si(Q₁)(Q₂)(Q₃), wherein Q₁ to Q₃ and Q₃₁ to Q₃₃ are each independently selected from a C₁-C₁₀ alkyl group, a C₁-C₁₀ alkoxy group, a phenyl group, a biphenyl group, a terphenyl group, and a naphthyl group.
 8. The organic light-emitting device of claim 1, wherein R₁ to R₄ and R₈ to R₁₁ are each independently selected from the group consisting of: hydrogen, deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amino group, an amidino group, a hydrazine group, a hydrazone group, a carboxylic acid group or a salt thereof, a sulfonic acid group or a salt thereof, a phosphoric acid group or a salt thereof, a C₁-C₁₀ alkyl group, and a C₁-C₁₀ alkoxy group; a phenyl group, a biphenyl group, a terphenyl group, a naphthyl group, a fluorenyl group, a spiro-fluorenyl group, a benzofluorenyl group, a dibenzofluorenyl group, a phenanthrenyl group, an anthracenyl group, a triphenylenyl group, a pyrenyl group, a chrysenyl group, a carbazolyl group, a dibenzofuranyl group, and a dibenzothiophenyl group; a phenyl group, a biphenyl group, a terphenyl group, a naphthyl group, a fluorenyl group, a spiro-fluorenyl group, a benzofluorenyl group, a dibenzofluorenyl group, a phenanthrenyl group, an anthracenyl group, a triphenylenyl group, a pyrenyl group, a chrysenyl group, a carbazolyl group, a dibenzofuranyl group, and a dibenzothiophenyl group, each substituted with at least one selected from deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amino group, an amidino group, a hydrazine group, a hydrazone group, a carboxylic acid group or a salt thereof, a sulfonic acid group or a salt thereof, a phosphoric acid group or a salt thereof, a C₁-C₁₀ alkyl group, a C₁-C₁₀ alkoxy group, a phenyl group, a biphenyl group, a terphenyl group, a naphthyl group, and —Si(Q₃₁)(Q₃₂)(Q₃₃); and —Si(Q₁)(Q₂)(Q₃), R₅ to R₇ are each independently selected from the group consisting of: hydrogen, deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amino group, an amidino group, a hydrazine group, a hydrazone group, a carboxylic acid group or a salt thereof, a sulfonic acid group or a salt thereof, a phosphoric acid group or a salt thereof, a C₁-C₁₀ alkyl group, and a C₁-C₁₀ alkoxy group; a phenyl group, a biphenyl group, a terphenyl group, a naphthyl group, a spiro-fluorenyl group, a benzofluorenyl group, a dibenzofluorenyl group, a phenanthrenyl group, an anthracenyl group, a triphenylenyl group, a pyrenyl group, a chrysenyl group, a carbazolyl group, a dibenzofuranyl group, and a dibenzothiophenyl group; a phenyl group, a biphenyl group, a terphenyl group, a naphthyl group, a fluorenyl group, a spiro-fluorenyl group, a benzofluorenyl group, a dibenzofluorenyl group, a phenanthrenyl group, an anthracenyl group, a triphenylenyl group, a pyrenyl group, a chrysenyl group, a carbazolyl group, a dibenzofuranyl group, and a dibenzothiophenyl group, each substituted with at least one selected from deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amino group, an amidino group, a hydrazine group, a hydrazone group, a carboxylic acid group or a salt thereof, a sulfonic acid group or a salt thereof, a phosphoric acid group or a salt thereof, a C₁-C₁₀ alkyl group, a C₁-C₁₀ alkoxy group, a phenyl group, a biphenyl group, a terphenyl group, a naphthyl group, and —Si(Q₃₁)(Q₃₂)(Q₃₃); and —Si(Q₁)(Q₂)(Q₃), and R₁₂ to R₁₅ are each independently selected from the group consisting of: a C₁-C₁₀ alkyl group and a C₁-C₁₀ alkoxy group; a phenyl group, a biphenyl group, a terphenyl group, a naphthyl group, a fluorenyl group, a spiro-fluorenyl group, a benzofluorenyl group, a dibenzofluorenyl group, a phenanthrenyl group, an anthracenyl group, a triphenylenyl group, a pyrenyl group, a chrysenyl group, a carbazolyl group, a dibenzofuranyl group, and a dibenzothiophenyl group; a phenyl group, a biphenyl group, a terphenyl group, a naphthyl group, a fluorenyl group, a spiro-fluorenyl group, a benzofluorenyl group, a dibenzofluorenyl group, a phenanthrenyl group, an anthracenyl group, a triphenylenyl group, a pyrenyl group, a chrysenyl group, a carbazolyl group, a dibenzofuranyl group, and a dibenzothiophenyl group, each substituted with at least one selected from deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amino group, an amidino group, a hydrazine group, a hydrazone group, a carboxylic acid group or a salt thereof, a sulfonic acid group or a salt thereof, a phosphoric acid group or a salt thereof, a C₁-C₁₀ alkyl group, a C₁-C₁₀ alkoxy group, a phenyl group, a biphenyl group, a terphenyl group, a naphthyl group, and —Si(Q₃₁)(Q₃₂)(Q₃₃); and —Si(Q₁)(Q₂)(Q₃), wherein Q₁ to Q₃ and Q₃₁ to Q₃₃ are each independently selected from a C₁-C₁₀ alkyl group, a C₁-C₁₀ alkoxy group, a phenyl group, a biphenyl group, a terphenyl group, and a naphthyl group.
 9. The organic light-emitting device of claim 1, wherein Ar₁ is selected from groups represented by Formulae 5-1 to 5-19, R₁ to R₁₁ are each independently selected from hydrogen, deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amino group, an amidino group, a hydrazine group, a hydrazone group, a carboxylic acid group or a salt thereof, a sulfonic acid group or a salt thereof, a phosphoric acid group or a salt thereof, a C₁-C₁₀ alkyl group, a C₁-C₁₀ alkoxy group, and a group represented by any of Formulae 5-1 to 5-11, R₁₂ to R₁₅ are each independently selected from a C₁-C₁₀ alkyl group, a C₁-C₁₀ alkoxy group, and a group represented by any of Formulae 5-1 to 5-11:

wherein, in Formulae 5-1 to 5-19, Y₃₁ is O, S, C(Z₃₃)(Z₃₄), N(Z₃₅), or Si(Z₃₆)(Z₃₇), Z₃₁ to Z₃₇ are each independently selected from the group consisting of hydrogen, deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amino group, an amidino group, a hydrazine group, a hydrazone group, a carboxylic acid group or a salt thereof, a sulfonic acid group or a salt thereof, a phosphoric acid group or a salt thereof, a C₁-C₂₀ alkyl group, a C₁-C₂₀ alkoxy group, a phenyl group, a biphenyl group, a terphenyl group, a naphthyl group, a fluorenyl group, a spiro-fluorenyl group, a benzofluorenyl group, a dibenzofluorenyl group, a phenanthrenyl group, an anthracenyl group, a pyrenyl group, a chrysenyl group, a pyridinyl group, a pyrazinyl group, a pyrimidinyl group, a pyridazinyl group, a quinolinyl group, an isoquinolinyl group, a quinoxalinyl group, a quinazolinyl group, a carbazolyl group, and a triazinyl group, e1 is an integer selected from 1 to 5, e2 is an integer selected from 1 to 7, e3 is an integer selected from 1 to 3, e4 is an integer selected from 1 to 4, e5 is an integer selected from 1 and 2, e6 is an integer selected from 1 to 6, and e7 is an integer selected from 1 to 9, and * indicates a binding site to a neighboring atom, and wherein when R₅, R₆, and/or R₇ are each independently a group represented by any of Formulae 5-4 to 5-6, Y₃₁ is O, S, N(Z₃₅), or Si(Z₃₆)(Z₃₇).
 10. The organic light-emitting device of claim 1, wherein Ar₁ is selected from groups represented by Formulae 6-1 to 6-26, R₁ to R₄ and R₈ to R₁₁ are each independently selected from the group consisting of hydrogen, deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amino group, an amidino group, a hydrazine group, a hydrazone group, a carboxylic acid group or a salt thereof, a sulfonic acid group or a salt thereof, a phosphoric acid group or a salt thereof, a C₁-C₁₀ alkyl group, a C₁-C₁₀ alkoxy group, and a group represented by any of Formulae 6-1 to 6-23, R₅ to R₇ are each independently selected from the group consisting of hydrogen, deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amino group, an amidino group, a hydrazine group, a hydrazone group, a carboxylic acid group or a salt thereof, a sulfonic acid group or a salt thereof, a phosphoric acid group or a salt thereof, a C₁-C₁₀ alkyl group, a C₁-C₁₀ alkoxy group, and a group represented by any of Formulae 6-1 to 6-11, 6-13 to 6-15, 6-17 to 6-20 and 6-23, and R₁₂ to R₁₅ are each independently selected from a C₁-C₁₀ alkyl group, a C₁-C₁₀ alkoxy group, and a group represented by any of Formulae 6-1 to 6-23:

wherein * in Formulae 6-1 to 6-26 indicates a binding site to a neighboring atom.
 11. The organic light-emitting device of claim 1, wherein the first compound is represented by one selected from Formulae 1-1 to 1-4:

wherein X₁, L₁ to L₃, a1 to a3, Ar₁, R₁₂ to R₁₄, R₁ to R₄, and b1 to b4 in Formulae 1-1 to 1-4 are the same as described in connection with Formula
 1. 12. The organic light-emitting device of claim 1, wherein the first compound is represented by one selected from Formulae 1-1(1) and 1-1(2):

wherein X₁, L₁, L₃, a1, a3, Ar₁, R₁ to R₄, b1 to b4, and R14 in Formulae 1-1(1) and 1-1(2) are the same as described in connection with Formula 1, R₃₁ to R₃₃ are each independently selected from hydrogen, deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amino group, an amidino group, a hydrazine group, a hydrazone group, a carboxylic acid group or a salt thereof, a sulfonic acid group or a salt thereof, a phosphoric acid group or a salt thereof, a substituted or unsubstituted C₁-C₆₀ alkyl group, a substituted or unsubstituted C₂-C₆₀ alkenyl group, a substituted or unsubstituted C₂-C₆₀ alkynyl group, a substituted or unsubstituted C₁-C₆₀ alkoxy group, a substituted or unsubstituted C₃-C₁₀ cycloalkyl group, a substituted or unsubstituted C₁-C₁₀ heterocycloalkyl group, a substituted or unsubstituted C₃-C₁₀ cycloalkenyl group, a substituted or unsubstituted C₁-C₁₀ heterocycloalkenyl group, a substituted or unsubstituted C₆-C₆₀ aryl group, a substituted or unsubstituted C₆-C₆₀ aryloxy group, a substituted or unsubstituted C₆-C₆₀ arylthio group, a substituted or unsubstituted C₁-C₆₀ heteroaryl group, a substituted or unsubstituted monovalent non-aromatic condensed polycyclic group, a substituted or unsubstituted monovalent non-aromatic condensed heteropolycyclic group, and —Si(Q₁)(Q₂)(Q₃), b31 is an integer selected from 1 to 4, and b32 and b33 are each independently an integer selected from 1 to
 5. 13. The organic light-emitting device of claim 1, wherein the second compound is represented by one selected from Formulae 2-1 and 2-2:

wherein, in Formula 2-1 and 2-2, X₂, X₁₁ to X₁₃, c1 to c3, R₅ to R₇, and b5 to b7 are the same as described in Formula 2, and R₁₆ to R₁₈ are each independently selected from hydrogen, deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amino group, an am idino group, a hydrazine group, a hydrazone group, a carboxylic acid group or a salt thereof, a sulfonic acid group or a salt thereof, a phosphoric acid group or a salt thereof, a substituted or unsubstituted C₁-C₆₀ alkyl group, a substituted or unsubstituted C₂-C₆₀ alkenyl group, a substituted or unsubstituted C₂-C₆₀ alkynyl group, a substituted or unsubstituted C₁-C₆₀ alkoxy group, a substituted or unsubstituted C₃-C₁₀ cycloalkyl group, a substituted or unsubstituted C₁-C₁₀ heterocycloalkyl group, a substituted or unsubstituted C₃-C₁₀ cycloalkenyl group, a substituted or unsubstituted C₁-C₁₀ heterocycloalkenyl group, a substituted or unsubstituted C₆-C₆₀ aryl group, a substituted or unsubstituted C₆-C₆₀ aryloxy group, a substituted or unsubstituted C₆-C₆₀ arylthio group, a substituted or unsubstituted C₁-C₆₀ heteroaryl group, a substituted or unsubstituted monovalent non-aromatic condensed polycyclic group, a substituted or unsubstituted monovalent non-aromatic condensed heteropolycyclic group, and —Si(Q₁)(Q₂)(Q₃); and b16 to b18 are each independently an integer selected from 1 to
 4. 14. The organic light-emitting device of claim 1, wherein the hole transport region comprises a hole transport layer and a hole auxiliary layer, and the hole transport layer comprises the first compound, and the hole auxiliary layer comprises the second compound.
 15. The organic light-emitting device of claim 14, wherein the hole auxiliary layer is between the emission layer and the first electrode, and the hole transport layer is between the hole auxiliary layer and the first electrode.
 16. The organic light-emitting device of claim 14, wherein the hole auxiliary layer directly contacts the emission layer.
 17. An organic light-emitting device comprising: a first electrode; a second electrode; an emission layer between the first electrode and the second electrode; and a hole transport region between the first electrode and the emission layer, wherein the hole transport region comprises a first compound selected from Compounds 101 to 109, and a second compound selected from Compounds 10 to 13, 15, 16, and 18-19: 